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Coronavirus Questions and Answers

Hopkins Experts Answer Your COVID-19 Questions

Coronavirus and Variants: The Basics

What is a coronavirus?

Coronaviruses are a family of viruses that typically cause mild respiratory infections like the common cold, but also more severe (and potentially deadly) infections. They are zoonotic diseases, meaning they are transmitted from animals to people.

SOURCE: Global Health NOW

Why is it called a coronavirus?

Coronaviruses are named after the Latin word corona, meaning “crown” or “halo,” because they have “crown-like spikes on their surface,” according to the U.S. Centers for Disease Control and Prevention.

SOURCE: Global Health NOW

What severe diseases are caused by coronaviruses?

A coronavirus that originated in China led to the Severe Acute Respiratory Syndrome (SARS) outbreak in 2003. Another coronavirus emerged in 2012 in Saudi Arabia, causing Middle East Respiratory Syndrome (MERS).

SOURCE: Global Health NOW

What’s the difference between coronavirus, SARS-CoV-2, and COVID-19?

The novel coronavirus responsible for this outbreak is known as SARS-CoV-2. The illness caused by the virus is called COVID-19.

More information can be found here: Naming the coronavirus disease (COVID-19) and the virus that causes it—WHO.

SOURCE: Global Health NOW

Could COVID-19 or a variant have been here before January 2020?

The earliest recognized cases of COVID-19 in the United States date back to January 14, 2020. At the start of the epidemic in the US—January - March, 2020—there was limited testing capacity so most testing was done only on people with symptoms and some who had recently traveled to certain areas of the world. 

A recent study of antibodies found evidence of SARS-CoV-2 infections weeks prior to the first recognized cases. In this study, residents of 9 states had antibodies as early as mid-December, 2019. 

SOURCE: Keri Althoff and the National Institutes of Health

What symptoms do coronaviruses typically cause? How is COVID-19 different?

Common signs of coronavirus infection include runny nose, cough, fever, sore throat, and shortness of breath.

COVID-19 can cause a wide range of signs and symptoms at varying levels of severity. The most common are fever, dry cough, and tiredness. Other symptoms include shortness of breath or difficulty breathing, muscle aches, chills, sore throat, headache or chest pain.

Other symptoms that aren’t as common include: gastrointestinal symptoms, new loss of smell or taste, skin changes (like lesions), confusion, and eye problems.

SOURCE: Mayo Clinic

Why does COVID-19 cause loss of smell?

Some patients can temporarily lose their sense of smell. This is because the “hook” of cells used by SARS-CoV-2 to latch onto and infect cells is up to 700 times more prevalent in the olfactory-supporting cells lining the inside of the upper part of the nose than in the cells lining the rest of the nose and windpipe that leads to the lungs. The supporting cells are necessary for the function/development of odor-sensing cells.


Why does COVID-19 cause shortness of breath?

COVID-19 can cause damage to the lungs that impedes their ability to remove oxygen from the air. A lot of patients develop what’s known as severe acute respiratory distress syndrome.

SOURCE: Jennifer Nuzzo

Does COVID-19 affect the heart?

One of the mechanisms that the SARS-CoV-2 virus uses to enter the lungs, called the ACE2 receptors, lives in the heart as well. When the virus enters the heart, it can cause clots, pulmonary embolism, or clots within the arteries of the heart causing a heart attack.

SOURCE: Public Health On Call

When and how should I seek medical attention?

Via the CDC:
If you develop any of the following emergency warning signs* for COVID-19, get medical attention immediately by calling your doctor’s office. Emergency warning signs include (but are not limited to):

  • Trouble breathing
  • Persistent pain or pressure in the chest
  • New confusion or inability to arouse
  • Bluish lips or face

Please call your medical provider for any other symptoms that are severe or concerning to you.

*This list is not all possible symptoms. Please call your medical provider for any other symptoms that are severe or concerning to you.


How are coronaviruses transmitted between people?

Although laboratory tests have shown that SARS-CoV-2 can remain on plastic and stainless steel for days, surfaces are not the main way that the virus spreads.

According to the WHO, the virus can spread from an infected person’s mouth or nose in small liquid particles when they cough, sneeze, speak, sing, or breathe. Current evidence suggests that the virus spreads mainly between people who are in close contact with each other, typically within six feet. A person can be infected when aerosols or droplets containing the virus are inhaled or come directly into contact with the eyes, nose, or mouth.

The virus can also spread in poorly ventilated and/or crowded indoor settings, where people tend to spend longer periods of time. This is because aerosols remain suspended in the air and can travel farther than three feet.

Vaccination, wearing a mask, staying at least six feet away from others, and avoiding prolonged contact (more than fifteen minutes) indoors with others are all helpful mitigation factors.


When a person breathes in a droplet containing the SARS-CoV-2 virus, how long does it take for the virus to start binding to receptors in the nose and throat? Is it seconds, minutes, hours, or days?

I think it's probably going to fall within minutes to hours. It's probably not instantaneous. I'm sure in a petri dish or in a laboratory, it can be done in seconds. But in your human body, it's a little bit more complicated because there's mucus. There are little hairs on your cells that are constantly beating, trying to remove debris like viruses. So it's hard to know exactly what the time course is down to the precise unit of measurement.

SOURCE: Amesh Adalja

What's the difference between being asymptomatic and presymptomatic?

Asymptomatic individuals test positive for COVID-19 but “lack symptoms that would indicate SARS-CoV-2 infection.” Some people may not experience any symptoms during the entire course of their COVID-19 infection.

But some people may develop symptoms days after a positive test. These individuals would be classified as having been presymptomatic at the time of their positive test; they will eventually develop symptoms.

SOURCE: Johns Hopkins Bloomberg School of Public Health

When people are asymptomatic, can they spread the virus?

Yes. A lab study suggests that as many as 50% of people who have the disease show no symptoms and are still able to spread the disease.

SOURCE: Gigi Gronvall

How long is an asymptomatic carrier shedding the virus?

Most people with COVID-19 can discontinue isolation 10 days after symptom onset. For people with no symptoms of COVID-19, isolation can be discontinued 10 days after the date of their first positive test.


If people are asymptomatic, how does the virus get from one person to another?

We now understand that the virus can be spread by people who have no symptoms at the time of transmission. Infected people can breathe out viral particles, which can infect others. Most documented transmission occurs over short distances, but some outbreaks have been reported where transmission occurred over a longer range. For this reason, experts caution about avoiding poorly ventilated indoor spaces, as these conditions may enable viral particled to build up and facilitate longer-range transmission.

Asymptomatic individuals test positive for COVID-19 but “lack symptoms that would indicate SARS-CoV-2 infection.” Some people may not experience any symptoms during the entire course of their COVID-19 infection.

But some people may develop symptoms days after a positive test. These individuals would be classified as having been presymptomatic at the time of their positive test; they will eventually develop symptoms.

Reviews have shown that most transmission from people who don’t have symptoms at the time of transmission occurs from people who turn out to be presymptomatic, not asymptomatic.

SOURCE: Jennifer Nuzzo

Is COVID-19 airborne?

New evidence points towards likelihood that the virus may be spread through aerosols that linger, not just droplets that fall.

Droplets caused by coughing and sneezing are still the main source of infection. Remaining six feet away from others means you are less likely to be exposed to droplets.

There can also be fomites, which is infectious material from droplets or aerosols that land on surfaces you might touch. Handwashing is very effective in this circumstance.

SOURCE: Public Health On Call Podcast

What is known about young children and whether they are carriers and can transmit the virus?

Young children can be infected and transmit to others. 

It continues to be the case that children often do not have any symptoms at all. If they do have symptoms, they're quite mild. This makes it hard to understand what transmission looks like in children.

There is a rare and dangerous condition in sick children called multi-system inflammatory syndrome in children (MIS-C) which is thought to be caused by an immune reaction to SARS-CoV-2.

SOURCE: Public Health On Call Podcast

Of those infected, what percentage will require hospitalization? And what percentage will require care in an intensive care unit (ICU)?

Hospitalization rates vary by age group and increase with age. Approximately 90% of hospitalized patients have one or more underlying conditions, the most common being obesity, hypertension, chronic lung disease, diabetes, and cardiovascular disease.

As of fall 2021, the vast majority of hospitalizations and deaths from COVID-19 were among unvaccinated people. 


Is COVID-19 worse than the flu?

Yes. COVID-19 is much deadlier than the flu. COVID-19 has a higher severe disease and mortality rate than influenza in all age groups, except perhaps children under the age of 12.

SOURCE: Andrew Pekosz

What does “recovered” mean?

The CDC advises:

You can be around others after:

  • 10 days since symptoms first appeared AND
  • 24 hours with no fever without the use of fever-reducing medications AND
  • Other symptoms of COVID-19 are improving*

*Loss of taste and smell may persist for weeks or months after recover and need not delay the end of isolation.

If you are unvaccinated and test positive for COVID-19 but have no symptoms, you can be with others after 10 days from your positive test. 


What is the possibility of reinfection after you have recovered from COVID-19?

It's difficult to confirm a case of reinfection. You need to have samples of sequencing from the first infection and again from the second infection to actually be able to tell if it's a different variant of the virus and not just the same persistent infection that's coming back. 

There are known cases of reinfection which illustrate that we don't know exactly how long immunity may last for COVID-19. 

The CDC recommends that all people, whether or not they have had COVID-19, take steps to prevent getting and spreading COVID-19. Wash hands regularly, stay at least six feet away from others whenever possible, and wear masks.

SOURCE: Public Health On Call Podcast

Is there evidence of a heightened risk to pregnant women?

Pregnant people are at an increased risk for severe illness from COVID-19 compared to non-pregnant people. Having certain underlying medical conditions and other factors, including age, can further increase a pregnant or recently pregnant person’s risk for developing severe illness.

Pregnant people with COVID-19 are also at increased risk for preterm birth (delivering the baby earlier than 37 weeks) and might be at increased risk for other poor pregnancy outcomes.

Pregnant and recently pregnant and breastfeeding people can receive a COVID-19 vaccine. 

Learn more about newborns and COVID-19 here


What exactly are SARS-CoV-2 variants of concern and variants of interest? 

Because so many SARS-CoV-2 variants have emerged, the WHO has instituted a system to classify them into two major groups: Variants of Concern (VOCs) and Variants of Interest (VOI). VOCs are variants that have clearly shown the ability to transmit more easily in humans, evade vaccine, or cause increased disease severity. VOIs are variants that have mutations that might make them more of a threat to humans, but the data has either not been collected or is inconclusive. There are many variants that don’t fall into either of these categories because viruses like SARS-CoV-2 tends to mutate at a frequent rate, but most of those mutations don’t affect how the virus circulates or causes disease.

The WHO made a new naming system for VOCs and VOIs that uses Greek letters in place of the formal scientific designation or place of identification of these variants. For example, the alpha variant used to be referred to as “UK variant” or “B.1.1.7” and the delta variant was the “India variant” or “B.1.617.2”. As of today, the alpha variant is the dominant variant globally but the delta variant seems to be spreading even faster than the alpha variant, so it is now the VOC that most public health officials worry about the most.

SOURCE: Andrew Pekosz

Are the new variants of SARS-CoV-2 more transmissable? 

Yes. There are currently two theories about what, specifically, makes some of these variants more transmissible. One is that variant viruses are “stickier,” meaning it requires a smaller amount of virus to cause infection because it’s better at adhering to your cells. Another theory is that variants causes people to harbor more virus particles in their noses and throats, which means more virus is expelled when people talk, cough, or sneeze.

Behavioral and situational factors could help a more transmissible variant spread even further, but wearing a mask, ensuring physical distance, and hand washing will still help.

SOURCE: Andrew Pekosz

Is there a difference between "more transmissable" and "more contagious?"

Transmission is often used when we talk about populations, while contagious is more often used when we are talking about an individual. They are interchangeable to some degree.

SOURCE: Andrew Pekosz

Is there any change in guidance for how to protect yourself and others from new variants of SARS-CoV-2? 

Masks, social distancing, and hand washing should work against the variants just as well. But higher transmission could mean more cases, which can increase risk for individuals and overwhelm hospital systems again, so it may be necessary to re-implement closures and restrictions to flatten the curve if it starts to rise.

Most importantly, COVID-19 vaccines—and in particular the mRNA vaccines—are showing good protection against the VOCs, so go and get your COVID-19 vaccine!

SOURCE: Andrew Pekosz

How common is it for a virus to mutate? Is it unusual to see new variants of SARS-CoV-2 take hold this soon?

All viruses mutate, and SARS-CoV-2 has been mutating at a pretty consistent rate since it entered the human population. 

This new variant has accumulated an extremely large number of mutations compared to other lineages. Usually we can follow the evolution of a virus because we find related viruses with fewer mutations. But with this virus, it seems to have just appeared with a lot of mutations. It will be important to determine how this virus got so many mutations without being identified sooner. 

SOURCE: Andrew Pekosz

Will the new variants eventually be more widespread than the current "wildtype" virus?

If the new variant is more transmissible than other SARS-CoV-2 lineages, it eventually could be the most commonly found lineage of SARS-CoV-2. However, while we still have so many people with no immunity to the virus, we should still see different lineages spreading in different parts of the world. 

SOURCE: Andrew Pekosz


Are some groups at a higher risk for severe COVID-19 illness?

Severe illness from COVID-19 can include: hospitalization, intensive care, a ventilator to help with breathing, or death.

Available information suggests that the following are at a higher risk for severe illness from the virus:

  • Older adults:
    • More than 80% of COVID deaths occur in people over age 65
    • More than 95% of COVID deaths occur in people older than 45
  • Many racial and ethnic minority groups and people with disabilities (due to long-standing systemic health and social inequities)
    • Studies have shown that people from racial and ethnic minority groups are also dying from COVID-19 at younger ages
  • People of any age with the following conditions:
    • Cancer
    • Chronic kidney disease
    • COPD
    • Immunocompromised state from solid organ transplant
    • Obesity (BMI of 30 or higher)
    • Pregnancy
    • Serious heart conditions, such as heart failure, coronary artery disease, or cardiomyopathies
    • Sickle cell disease
    • Type 2 diabetes mellitus

Adults of any age with underlying medical conditions are at increased risk for severe illness. COVID-19 vaccines are recommended for and can be administered to most people with underlying medical conditions. In some cases, people with certain medical conditions that cause a suppressed immune system should receive a third dose of either the Moderna or Pfizer vaccine as soon as 28 days after the second dose. 

For a full list and recommended precautions, please visit the CDC resource.

SOURCES: CDC, Johns Hopkins Medicine

Do higher-risk patients ever have mild coronavirus, or is it always the case that people who are at higher risk get very sick?

They do. Certainly, people of advanced age and people with underlying conditions statistically are among those mostly likely to be hospitalized and die, but that’s not always the case. People in both of those categories also may have mild infection or may become sick and survive their illness.

SOURCE: Jennifer Nuzzo

Do we know, at this point, who is at risk of developing long COVID? 

At this point, there’s no data on who is more likely to get long COVID. But there are studies underway that are looking at whether vaccination can help with long COVID.

It’s important to note that regardless of whether or not vaccines can help with symptoms, long-hauler COVID patients should get vaccinated for COVID. This will help prevent reinfection as we still don’t know how robust the immune response is in long-haul patients.

SOURCE: Gigi Gronvall

Can children develop long COVID? 

Recent data indicates that 2 - 10% of young COVID-19 survivors—some as young as 9 years old—are estimated to experience lingering symptoms.

SOURCE: Hopkins Bloomberg Public Health Magazine

Should people on immunosuppressive drugs stop taking their medications?

Most research suggests that individuals on chronic immunosuppressive medicines have a similar likelihood of severe COVID disease, if they get infected, as those who are not on such medications. Individuals concerned about the potential risks of these medicines should talk with their healthcare provider, as well as use evidence-based approaches to reduce the risk of COVID infection such as social distancing and mask wearing.

COVID-19 vaccines are recommended for and can be administered to most people with underlying medical conditions. In some cases, people with certain medical conditions that cause a suppressed immune system should receive a third dose of either the Moderna or Pfizer vaccine as soon as 28 days after the second dose. 

SOURCES: Caleb AlexanderJohns Hopkins Medicine 

How is COVID-19 impacting people without spleens? (With certain bacterial diseases, people without spleens can get very severe infections.)

There is not specific data around this. In general, we think of people who do not have a spleen or whose spleen is not functioning well as being immunosuppressed. I would be more cautious with those individuals and more aggressive in their care. Those individuals would want to have more social distancing than the average person.

SOURCE: Amesh Adalja

Are women taking oral contraceptives more at risk from blood clotting from COVID-19?

There is an elevated risk of clotting from oral contraceptives. COVID will synergize with whatever other propensity you have to get clots so someone on birth control may be more likely to clot than the average person.

SOURCE: Amesh Adalja


What are all the different kinds of COVID tests?

Testing for COVID can be divided into two main groups: testing for active SARS-CoV-2 infection or testing for past SARS-CoV-2 infection. Active infection indicates that a person has virus that is replicating and that they could infect others. Past infection indicates that an individual has recovered from COVID-19 and has no actively replicating virus.

To test for active infection, diagnostic antigen or molecular tests are used. 

To test for past infection, serology tests are used. 

Learn more about the specific types of antigen, molecular, and serology tests, how they are collected, and when each should be used here

SOURCE: The Center for Health Security Testing Toolkit

What kind of COVID test should I get?

The Center for Health Security has created a flowchart to help you determine what COVID-19 test type you may need. 

In general, if you may have a current COVID-19 infection and you are experiencing symptoms, you should seek an antigen or molecular diagnostic test. These tests may be referred to with terms like: PCR, qPCR, rRT-PCR, antigen, rapid antigen test, RPA, RT-LAMP, and CRISPR.

SOURCE: The Center for Health Security

What's the difference between a rapid test versus a PCR test that takes 24 hours or longer?

PCR tests have to be done in the lab. That test has an amplification step so it can find small amounts of virus in somebody’s nose. That means you can detect the infection a little bit earlier on.

The rapid antigen test requires a lot of virus to see a positive result because there’s no amplification step. The good part about that is that if you test positive in this fast test, then you really know you should not be around other people. You are infectious and need to isolate immediately.

There are pros and cons: you can catch an infection earlier with a PCR test, but you get the immediate actionable result with the rapid antigen test. They’ve been shown to be pretty equivalent in lots of different scenarios.

SOURCE: Gigi Gronvall

If I'm fully vaccinated, how reliable is any COVID test? 

COVID-19 tests with up-to-date FDA EUA are still reliable at detecting COVID-19, whether symptomatic or asymptomatic. The FDA keeps a running list of tests that have shown decreased ability to detect SARS-CoV-2 variants, such as the delta variant.

Otherwise, COVID-19 tests are still an important tool for disease transmission among vaccinated and unvaccinated persons. Only around 0.5% to 1.0% of fully vaccinated persons appear to test positive for COVID-19, a situation known as a “breakthrough case.” Since breakthrough cases exist on a spectrum of symptoms, ranging from fully asymptomatic to more worrisome disease, regular testing remains a key component of the pandemic response strategy to identify these cases. If someone has a known exposure to someone with COVID-19, the CDC recommends that they should be tested regardless of vaccination status.

SOURCE: Amanda Kobokovich

Are there at-home COVID tests available?

It’s now possible for people to buy tests at their local pharmacy. There’s more privacy that way—you don’t have to go to a testing site and can just find out [on your own]. Several different brands will be available soon.

These are rapid antigen tests—you get your results in 20 minutes. And if you test positive with those, you should isolate. You should not be around other people, because you’re probably contagious.

SOURCE: Gigi Gronvall

I'm thinking of ordering some at-home tests. Under what circumstances are they the most helpful?

As the cost of at-home testing hopefully decreases in the coming months, these tests can be incredibly useful for routine checks before heading into the office, going to school, or visiting family and friends. 

Some school districts have already implemented a “test-to-stay” policy in which students who have been identified as a close contact of a positive case may continue to attend in-person learning as long as they test negative. Many of these “test-to-stay" policies currently rely on laboratory-verified PCR or rapid antigen tests, but parents of children in districts not using this strategy could use at-home testing to regularly check their family throughout the school year. At-home tests could be quite useful in this environment as long as testing cost is reasonable for families and the tests are readily accessible in local stores or online. 

SOURCE: Amanda Kobokovich

If I test positive for COVID on an at-home test, what should I do? Is there anyone I need to call?

If you test positive using an at-home test, you should follow-up with your health care provider and follow the instructions on your test kit to report your results to the local health department. You should isolate in your home according to CDC guidelines and reduce contact with anyone living in your household.

After you’ve reported your results or spoken to your health care provider, you may be contacted by your local health department to alert any close contacts with whom you may have recently interacted. Always stay in touch with your health care provider, monitor your symptoms, and seek medical attention if necessary

SOURCE: Amanda Kobokovich

When should I NOT rely on an at-home test? When is it best for me to be tested at a clinic or a place that can process the test in a lab?

If you are planning on traveling internationally, you may need to present a laboratory-verified test as part of entry screening requirements, depending on your destination.

Large venues and sporting events are increasingly requiring verified testing results for entry, which rules out most at-home test results, unless they are reported and independently verified using associated apps or telehealth providers. 

There might also be situations in which you would feel more confident in receiving laboratory-verified results before visiting immunocompromised or high-risk family members. At-home tests with FDA EUA have a high level of accuracy and track well against results from laboratory-based tests, but if you have difficulty swabbing yourself or would feel more confident in a professional performing the test, you can always find testing resources in your area.

SOURCE: Amanda Kobokovich

I got an antibody test after I got vaccinated and it came back negative. Does that mean the vaccine didn’t work for me?

Not all antibody tests are looking for the part of the virus that the vaccine is made from, so all that test was telling that person was that they never had COVID.

None of the tests right now are authorized to determine how well you responded to the vaccine. But the vaccines are really effective. If you indeed took the vaccine, you don’t need a test from your pharmacy to confirm you’re vaccinated.

SOURCE: Gigi Gronvall

Do different variants of SARS-CoV-2 affect testing accuracy?

Because of the diversity and breadth of tests currently available, most diagnostic tests can still be reliably used to diagnose the variant strains. 

SOURCE: The Center for Health Security

What does testing tell us the spread of the virus? What is “percent positive”?

Public health officials rely on testing results to track the state of the pandemic and policymakers use this information to guide decisions on reopening schools and businesses.

Percent positive is the percentage of all coronavirus tests performed that are actually positive, or: (positive tests)/(total tests) x 100%. The percent positive (sometimes called the percent positive rate or positivity rate) helps public officials understand the current level of SARS-CoV-2 transmission in the community and whether or not a community is doing enough testing for the number of people who are getting infected.

SOURCE: David Dowdy and Gypsyamber D’Souza

If you are tested and the test is negative, do you still have to be quarantined?

Yes, if you are unvaccinated. An unvaccinated person exposed to a person with COVID-19 needs a 10-day quarantine regardless of test results. 

If you are fully vaccinated and exposed to COVID-19, you should be tested 3-5 days after exposure and wear a mask in public indoor settings for 14 days or until you receive a negative test result. 

SOURCE: Joshua Sharfstein, CDC

Can a COVID test read negative if it takes too long to process the sample?

This has not happened with PCR tests. Antigen tests, or those that look for antibodies, could potentially read positive falsely if they are not processed in a certain period of time.

SOURCE: Crystal Watson

Prevention and Infection Control

How can I protect myself against coronaviruses?

The best way to protect yourself from COVID-19 is to get vaccinated
The CDC recommends the following for unvaccinated people:

  • Regularly and thoroughly wash your hands with soap and water for at least 20 seconds or clean them with a 60% alcohol-based hand sanitizer. Avoid touching your eyes, nose, and mouth with unwashed hands.
  • Maintain at least six feet of distance between yourself and anyone who doesn’t live in your household. If someone in your home is sick, maintain six feet of distance from the sick person if possible.
  • Cover your mouth and nose with a mask when around others.
  • Cover your mouth and nose with your bent elbow or a tissue when you cough or sneeze, then dispose of the used tissue immediately.
  • Clean and disinfect frequently touched surfaces daily, including doorknobs, tables, light switches, countertops, handles, desks, phones, keyboards, toilets, faucets, and sinks.
  • Stay home if you feel unwell. If you have a cough, fever, and difficulty breathing, call your health provider.

There is growing evidence that wearing masks protects the wearer as well as others.


Does wearing a mask protect me from getting sick?

There is growing evidence that wearing masks protects the wearer as well as others.

Masks—no matter what kind of mask—filter out the majority of viral particles.

SOURCE: Public Health On Call

Is hand sanitizer effective to protect against COVID-19?

If soap and water are not readily available, use a hand sanitizer that contains at least 60% alcohol. Cover all surfaces of your hands and rub them together until they feel dry.


Is there anything I can do to prepare just in case I or someone in my household gets COVID?

The best thing you can do is to follow prevention guidelines like wearing a mask, practicing social distancing, and avoiding close contact with others not in your household.

But there are other things you can do to be prepared in the event of illness such as knowing where and how to access testing, having a plan for quarantine and isolation, and understanding your employer's sick leave policy. Read more about how to prepare for COVID here

SOURCE: Johns Hopkins Bloomberg School of Public Health

What should I do if I have a confirmed COVID-19 diagnosis?

If you are unvaccinated and have a confirmed COVID diagnosis via a positive test, it's important to isolate yourself immediately, answer your phone in case a contact tracer is trying to reach you, and call your doctor or health care provider if you have one.

Read more information on what to do if you have COVID here

SOURCE: Johns Hopkins Bloomberg School of Public Health

What should I do if I am fully vaccinated and exposed to COVID?

Fully vaccinated people who have come into close contact with someone with suspected or confirmed COVID should be tested 3-5 days after exposure and wear a mask in public indoor settings for 14 days or until they receive a negative test result.


Cleaning produce brought home from the grocery store: Should you do anything differently or use any particular cleaning products?

Here is general guidance on fruits and vegetables: (via CDC). There is not specific guidance for coronavirus. In general, the risk of transmission is low, but will be reduced further with cooking.

SOURCE: Joshua Sharfstein

Is the public water supply safe from COVID-19?

There is no evidence of transmission through the public water supply.

SOURCE: Joshua Sharfstein

If two people are positive, can they quarantine together or do they have to be separated?

If multiple people in a household have confirmed COVID-19, it’s fine for them to isolate together.

If a household member has COVID-19, that person should be isolated from others in the home, and the entire household should quarantine for 14 days.

SOURCE: Johns Hopkins Bloomberg School of Public Health

What should you do if someone in your household is sick?

If someone in your household is sick, that person should be isolated as much as possible from unvaccinated or high-risk household members and all unvaccinated members of the household should follow guidance for quarantining.

SOURCE: COVID-19 Infection Control in Your Home 

Does wearing two masks offer better protection than wearing just one?

If you do not have access to an N95 mask, one way to boost the protection of a cloth mask is by wearing a surgical mask underneath it. 

Important note: This guidance is not intended for a health care workers. That guidance can be found here.

SOURCE: Johns Hopkins Bloomberg School of Public Health

Are my pets at risk of getting sick?

Keep your pets—just keep your distance if you have COVID-19.

While few pet animals have been shown to carry SARS-CoV-2, and even fewer have gotten sick, it is possible for owners to transmit the COVID-19 virus to their pets. Cats and ferrets may be more likely than other kinds of pets to contract the virus. Some dogs have tested positive too.

The recommendation right now is to keep your distance from pets if you are diagnosed with COVID-19 or have been exposed to someone who tested positive. If you have COVID-19 and your pet is sick, please contact your veterinarian.

SOURCE: Meghan Davis

Can you get COVID-19 from second-hand smoke?

If someone is smoking a cigarette and coughing at the same time, maybe, but there’s not a biological mechanism for how the virus would be in the smoke.

SOURCE: Amesh Adalja

Does prone body position help very severely ill coronavirus patients in the intensive care unit?

There are reports that this can be helpful and there are more proning studies going on. The challenge with proning is that it is staffing intensive. You need a lot of staff to put people in the proning position and keep them that way—and a lot of PPE to do this safely.

SOURCE: Lauren Sauer

Wet markets in China are widely believed to be a source of new infections, including coronavirus. Should they be shut down?

Wet markets have come up in a number of contexts—certainly with COVID-19, and the 2003 SARS epidemic was linked to a wet market. The challenge with COVID-19 is that we don’t actually know much about the wet market that was involved. We know that the initial cluster of patients seen by clinicians had an occupational connection there. But we don’t fully know if and how they became infected at the wet market. It’s possible that the virus was circulating in the population and somebody who had it spread it at the wet market. We don’t know that it came from the animals there.

Wet markets have been identified as places of risk for the potential of animal viruses to spill over into human viruses, and there’s an active conversation around what to do about that. Some want to shut them down but worry it will just drive the practice underground in a way that authorities are unable to regulate. Others advocate for more regulatory approaches, so that when they occur, they occur as cleanly as possible.

SOURCE: Jennifer Nuzzo


Can people expect to be immune once they’ve had the virus?

If you’ve been infected, you have some protection but that immunity has limits. The biggest limit is that it doesn’t last long: immunity from natural infection starts to decline after 6-8 months.

Studies have shown that people who have been infected can benefit significantly from vaccination. It gives them a strong, lasting immunity boost.

SOURCE: Sabra Klein

Treatments and Vaccines

What treatments are there for coronaviruses?

There is no cure yet for COVID-19 and only one treatment, a drug called remdesivir, has been approved by the FDA but research suggests it may provide only a modest benefit to patients.

Molnupiravir is an oral antiviral COIVD-19 drug undergoing review by the FDA. The goal of oral antivirals is to prevent people from getting sicker so they rehabilitate faster. People who are newly infected with the coronavirus or are newly symptomatic begin taking the drugs within three to five days of symptoms starting. It's likely that molnupiravir will be given to nonhospitalized adults with mild to moderate COVID-19 who are within five days of symptom onset and have at least one risk factor for severe disease. 

The New York Times Coronavirus Drug and Treatment Tracker is following treatments for effectiveness and safety. This resource is updated frequently.

The Novel Coronavirus Research Compendium (NCRC) is a literature curation effort by over 50 faculty members with collaborating institutions that review thousands of papers about COVID-19 research, including treatment, each week.

SOURCE: Johns Hopkins Bloomberg School of Public Health and Public Health On Call

How does convalescent plasma work?

Convalescent serum is made from the antibodies made by people who have already recovered from COVID-19. It’s possible that giving these antibodies to people at high risk for exposure (like household contacts or health care workers), or to people early in infection, will be beneficial.

By the spring of 2021, over 500,000 patients were treated with convalescent plasma. Clinical trials have had mixed results, but some studies show a reduction in mortality if administered early in the course of infection.

SOURCE: Arturo Casadevall

Will I still need to wear a mask after I get both doses of the vaccine?

The CDC updated its guidance for individuals who have been fully vaccinated with a COVID-19 vaccine. Fully vaccinated people no longer need to wear a mask or physically distance—except where required by federal, state, local, tribal, or territorial laws, rules, and regulations including businesses and workplace guidance.

SOURCE: Gigi Gronvall

Will an MMR booster provide protection from COVID-19?

There is no evidence that an MMR booster will provide any protection from SARS-CoV-2. But, it is still important for people, and kids in particular, to get the MMR vaccine to prevent those diseases.

SOURCE: Crystal Watson

Is there evidence for using hydroxychloroquine as a treatment for COVID-19?

Early questions about whether hydroxychloroquine might be of help to patients with COVID-19 have been addressed by high-quality research, and the results do not support the medication’s use. In June, the U.S. Food and Drug Administration found “no benefit for decreasing the likelihood of death or speeding recovery,” and revoked the medication’s authorization for use in COVID-19.

SOURCE: Joshua Sharfstein

Is it a good idea to get a flu shot?

It will be important to increase the proportion of the population vaccinated against flu as a means to protect ourselves and our communities, but also to save hospital capacity to treat those with COVID-19.

SOURCE: Public Health On Call podcast

What are mRNA vaccines and how are they different from other types of vaccines?

All vaccines deliver a viral protein that causes the person being vaccinated to make an immune response. There are different ways to do this: one is to give the whole, inactivated virus so that is doesn't make the person sick. 

Another way is to deliver the nucleic acid that encodes the protein and let the [vaccinated person's] cells actually make the protein. RNA is the nucleic acid that codes for proteins that cells make. It has all the information needed to be able to synthesize the protein. [mRNA vaccines] deliver the RNA that encodes the viral protein you're interested in and lets the cell actually make that protein to then stimulate the immune system. 

SOURCE: Public Health On Call Podcast

Are mRNA vaccines new?

Decades of research went into perfecting the mRNA technology platform. mRNA was first discovered in the 1930s and the first vaccines were tested in mice in the 1990s.

Although the first mRNA vaccines for humans were tested in 2013—and these were rabies vaccines—the technology had no commercial development opportunities until the COVID-19 pandemic which spurred manufacturers to develop dozens of vaccines against SARS-CoV-2 and brought tremendous increases in funding.

This is a technology that has been well studied and already, vaccine manufacturers are developing mRNA vaccines to protect against other diseases such as the flu and HIV. It's a new era for vaccine technology and production, and a testament to scientific progress and decades of research. 

SOURCE: Chris Beyrer

What makes mRNA vaccines so beneficial?

[mRNA vaccines] have several advantages. Because the cell itself is going to make the protein, it's much more likely to be the native protein or have the right properties that the virus would also have. 

Another big advantage is that they're fast to make. If you have the basic platform that [allow you] to insert the sequence for your particular protein of interest, you can just take [that] out and put another one in. It's very fast to substitute in a new, different coding sequence for a protein.

SOURCE: Public Health On Call Podcast

Will mRNA vaccines work against different variants of COVID-19? 

So far, mRNA vaccines appear to be quite effective against different variants of COVID-19. But this could change and if new mutations notably alter the protein’s structure, new variants could elude the antibodies elicited by vaccines for other variants.

Fortunately, mRNA vaccines are well-suited for keeping up with sudden changes like these. The mRNA itself is manufactured via a standardized process in which the core ingredient is a DNA sequence encoding a specific viral protein. This means vaccine makers can update the vaccine for new strains by tweaking the “recipe” to encode a new protein.

SOURCE: Gigi Gronvall

Why were we able to adapt the mRNA platform for the virus that causes COVID-19 but not flu or other viruses? 

The first mRNA vaccines using these fatty envelopes were developed against the deadly Ebola virus, but since that virus is only found in a limited number of African countries, it had no commercial development in the U.S.

This is a technology that has been well studied and already, vaccine manufacturers are developing mRNA vaccines to protect against other diseases such as the flu and HIV. It's a new era for vaccine technology and production, and a testament to scientific progress and decades of research. 

SOURCE: Chris Beyrer

Will we use the mRNA platform to make other kinds of vaccines?

Already, vaccine manufacturers are developing mRNA vaccines to protect against other diseases such as the flu and HIV. It's a new era for vaccine technology and production, and a testament to scientific progress and decades of research. 

SOURCE: Chris Beyrer

If a vaccine is showing "95% efficacy", does that mean that 5% of people who are vaccinated would still get COVID? 

There's a lot of different ways that people calculate efficacy. Think about it as if you were vaccinated and your friend was not vaccinated, and you were both exposed to the same amount of virus. Your risk of coming down with COVID is 95% reduced compared to your unvaccinated friend. 

Some other vaccines offer 50% efficacy. When you think of it in those terms—if you have a 50% reduced risk of coming down with disease [compared to] an unvaccinated person exposed to the same amount of virus—it's still a pretty good risk calculation for yourself. 

95% efficacy is amazing. That's more like the efficacy that we see for childhood vaccines—diphtheria, MMR, tetanus, or measles. 

SOURCE: Gigi Gronvall

How do we know that the vaccines are safe, given how quickly they were developed?

As of May 2021, more than 100 million Americans have been fully vaccinated. Public health agencies have been closely watching for any safety signals and we have safety data going back as far as August 2020 when Pfizer and Moderna first began vaccinating Phase 3 clinical trial participants.

In the United States, the FDA has required the same large clinical trial that it would otherwise require for a vaccine. We didn’t do what some other countries did and approve it just based on some blood test results; we actually looked at tens of thousands of people to see whether or not it prevented the disease.

One of the ways the process was sped up is that the taxpayers put a lot of money into this program—that was run out of the White House—to allow companies to basically start each part of the process right from the beginning.

Typically, what would happen is a company might do one study and see whether it works. If it doesn’t work, then they’re done. If it does work, then they start planning the next phase. And if that phase works, then they start planning the next. Everything is A, then B, then C. But with the money that the taxpayers put forward, the companies were able to do A, B, and C all at once. So, they started that first phase and if that worked, they were ready to get going on that second phase. If it wasn’t going to work, they would have lost all the money [spent] preparing for the second phase.

But what they gained was time. They were able to move from A, to B, to C so much quicker because they didn’t have that period in between where they were assessing and figuring out what kind of investment [would be needed] for the next round.

SOURCE: Joshua Sharfstein and Johns Hopkins Bloomberg School of Public Health

There is misinformation circulating that COVID-19 vaccines contain mercury, anti-freeze, animal blood, or even formaldehyde. What is behind these claims?

COVID vaccines are new, but these kinds of concerns about vaccines go back for a long time. These are often intentionally a misconstruction of information by people who are anti-vaccine. 

Do they include animal blood? Do they include formaldehyde? No, they don't. Some [vaccines] do have preservatives, but all of them have been tested many times and have a good safety record, particularly in the quantities that are in the vaccine. A lot of times, people forget that we ourselves are made up of chemicals, and some of these things in the vaccine, there are sometimes more of them in your own body naturally. 

It's important to be aware of your sources of information about the vaccine and also to recognize that there are groups that are intentionally poisoning the information atmosphere with things that are not true about the vaccine. Some don't really care about vaccines and are not really “anti-vaccine.” They're just really trying to sow discord.

A good hint of whether the information comes from a source that's intending to sow discord is if it makes you angry, if it inspires a powerful emotion. Just take the next step and look at your source. See if [the information] is coming from a place where there are people who are experts in that topic, who can address the concerns but without trying to manipulate you.

I've even heard [the claim] that there was some sort of chip in the vaccine—that is not possible and not something that is in these vaccines

SOURCE: Gigi Gronvall

Can protection from mRNA vaccines work against new variants of the virus?

So far, it looks like the mutations that are in the spike protein in these different variants are not going to let the virus escape the vaccine. This could change—particularly as SARS-CoV-2 continues to spread throughout the world, with each new host creating opportunities for mutation. If these mutations notably alter the protein’s structure, new variants could elude the antibodies elicited by vaccines for other variants.

Fortunately, mRNA vaccines are well-suited for keeping up with sudden changes in the viral landscape. The mRNA itself is manufactured via a standardized process in which the core ingredient is a DNA sequence encoding a specific viral protein. This means vaccine makers can update the vaccine to fend off new strains by simply tweaking the “recipe” to encode a new protein.

If this virus becomes endemic, it might be that new vaccine variants will need to be rolled out to match the variants that take root. 

SOURCE: Gigi Gronvall

What are randomized control trials?

A randomized control trial is a study design where a patient is randomized to either option one or option two, sometimes multiple options, and sometimes one of those options is a placebo. That study design allows us to control for factors that may influence our ability to see the benefits and the risks associated with something like a treatment.

It’s really important in this setting because we don’t know much about COVID-19. The design is how we identify medical countermeasures, vaccines, medications.

SOURCE: Lauren Sauer

Do the COVID-19 vaccinations impact fertility in men and women?

There is no basis for believing that they impact fertility. Of course, all things will be evaluated eventually, but this is a vaccine that has been described as a Snapchat message to the immune system. It is basically some mRNA that gets into the cells, triggers this immune response, and then it degrades, and then it’s gone. It’s a very temporary thing that gets into the body to help the immune system be able to recognize the coronavirus. It would certainly not be anticipated to have any kind of long-term effect like infertility.

SOURCE: Joshua Sharfstein

Should pregnant women get vaccinated for COVID-19?

At this stage, there is no reason for pregnant women not to get vaccinated. We know that pregnant women are at increased risk for more severe outcomes from COVID-19. They’re more likely to be hospitalized than nonpregnant women. And we know the vaccines are safe and effective. Vaccines can, at least, reduce the severity of disease among pregnant women, resulting in improved or normal pregnancy outcomes. This idea that someone who’s pregnant should roll the dice and risk getting infected rather than getting vaccinated is not a good decision.

SOURCE: Sabra Klein

Should I expect side effects from COVID-19 vaccines?

Side effects may vary with the type of COVID-19 vaccine. We know the most about side effects following vaccination with the Pfizer and Moderna messenger RNA—or mRNA—vaccines. 

The most common side effect is soreness at the site of injection. Other side effects include fatigue, headache, muscle aches, chills, joint pain, and possibly some fever.

SOURCE: William Moss

How long do side effects from COVID-19 vaccines last?

Usually 24 to 48 hours, and no more than a few days.

SOURCE: William Moss

Since COVID-19 vaccines come in two doses, will I experience the same side effects after each dose?

Side effects were more frequent after the second dose in the vaccine trials.

SOURCE: William Moss

Do side effects differ from one manufacturer's vaccine to another?

Side effects are similar after the Pfizer and Moderna mRNA vaccines but could differ with other types of vaccines.

SOURCE: William Moss

Can side effects be more pronounced in people who are at higher risk of severe COVID-19 disease, like those who are older or who have comorbidities?

No—in fact, vaccine side effects have been less frequent and severe in adults older than 55 years in the vaccine trials.

SOURCE: William Moss

How do I know if my side effects are normal or if I should alert my doctor or health care provider?

You will be told about the side effects of the vaccine and when you should consult a health care worker at the time you are vaccinated.

The Centers for Disease Control and Prevention advises that you should contact your doctor or health care provider if the redness or tenderness where you got the shot increases after 24 hours, or if your side effects are worrying you or do not seem to be going away after a few days.

SOURCE: William Moss

Is it safe to take acetaminophen or ibuprofen with vaccination?

There are no known safety issues with taking acetaminophen or ibuprofen with vaccination. Some experts have expressed concern that taking these medications might interfere with the immune response to the vaccine, but there is not data available to address this question directly.

As a result, it is generally recommended to take these medications only if necessary. The CDC says, "If you have pain or discomfort, talk to your doctor about taking an over-the-counter medicine, such as ibuprofen or acetaminophen." People who suffer specific medical complications of fevers should discuss a plan for using fever-reducing medications with their physicians before vaccination. 

SOURCE: Joshua Sharfstein

Is it possible to contract COVID-19 between vaccine doses? 

Yes—and this is why it is important to continue to wear a mask, practice social distancing, and wash your hands. 

The first dose will not provide complete protection, and it will take about seven days after your second dose before you will achieve a full protective level of immunity that develops in about 95% of vaccine recipients. If you are exposed to SARS-CoV-2 before this time, it is possible that you could develop COVID-19. 

Even once you have received both doses of the COVID-19 vaccine, it will still be important to continue practicing public health mitigation strategies like masks and distancing until the pandemic is under control and we know more about how the vaccines prevent transmission. 

SOURCE: William Moss

How will I know whether I am experiencing side effects or possible COVID-19 infection?

The side effects of the vaccine typically start within 12 to 24 hours of vaccination, but it may be difficult to tell the two apart if you become infected between vaccine doses.

If you experience side effects that last beyond 48 hours, you should contact your doctor or medical provider for advice. 

SOURCE: William Moss

Why do some COVID-19 vaccines require two doses?

The second dose boosts the immune response so that people can fight off infection of the actual coronavirus. There is clearly some protection from the first shot; how much there is, though, isn’t known. There will be more research done to see whether one shot might be enough, but for now, the evidence is really about two shots.

SOURCE: Joshua Sharfstein

Should people who already had COVID-19 and recovered still be vaccinated?

Yes! Prior infection with COVID-19 does offer some protection, but it’s limited: Immunity from natural infection starts to decline after 6-8 months.

Studies have shown that people who have been infected can benefit significantly from vaccination. After receiving the first dose of the Pfizer or Moderna vaccine, they have immunity levels comparable to those of uninfected people who have received their second dose.

SOURCE: Sabra Klein

If I've had COVID, how long should I wait to get vaccinated? Is it ok to get my first dose if I no longer have symptoms? 

The basic standard requirements are that if you are in that period where you’re sick and could be spreading COVID to stay home until you get better, which I think is around 10 days and no symptoms—then it’s fine to get vaccinated.

[Some] people have said you’re probably relatively protected from another infection for a couple months after that infection and, if you want to wait a couple of months to get vaccinated, you can do that. But there’s no requirement to do that. It’s perfectly fine to get vaccinated.

There are people who may get COVID right after their first shot, before there’s any protection, and they could get vaccinated for their second shot on time if they want, with one exception: If they’ve been treated for that COVID infection with antibody treatment, then there’s a recommendation to wait 90 days so that that antibody treatment doesn’t interfere with the vaccination.

SOURCE: Joshua Sharfstein

Since there’s a chance I could get sick from the vaccine’s side effects, is it better to get infected with COVID-19 naturally than to get vaccinated? 

No. Vaccines are tested for their safety in ways we could never do with a natural viral infection. A lot of what are referred to as side effects are the precise things we experience to a greater degree when we are infected: fever, headache, malaise, gastrointestinal issues, etc. With infection, you don’t know how bad it’s going to be. By not getting vaccinated, you’re rolling the dice. You may become severely ill. You may have to be hospitalized. You may die. There’s also the risk of long COVID

SOURCE: Sabra Klein

Do I still have to wear a mask and practice social distancing after I get vaccinated? 

Data shows that COVID-19 vaccines are highly effective at protecting vaccinated people against severe COVID-19. The CDC does still recommend that, in order to reduce the risk of being infected with the Delta variant, fully vaccinated people should wear masks and indoors in public in areas with substantial or high transmission. 

Those with weakened immune systems, underlying health issues, or who live with or care for individuals who are at high risk may choose to wear a mask regardless of activity or transmission level. 


If I am fully vaccinated and I catch the delta variant, will I acquire additional immunity?

It's likely that when you get a natural infection, you are going to be exposed to proteins of the virus that are not contained in the vaccine. So, you likely will get a boost to your immunity, and maybe some different elements of your immunity will get stimulated with the natural infection. It might not necessarily be better than what's in the vaccine,  but it's probably different immunity because different proteins of the virus are seen by your immune system.  

SOURCE: Amesh Adalja

Can the same awful things that happen with COVID infection in an unvaccinated person also happen with breakthrough infections, like long COVID or, potentially, an increased risk for heart attacks and strokes because of the changes to the vascular walls that might result? 

Generally, the answer is no. That's the whole goal of the vaccines: not to prevent every breakthrough infection but to make breakthrough infections something that's mild, something that's not really clinically that significant, and that's what we're seeing. 

That doesn't mean that there haven't been breakthrough infections that are severe. I've taken care of three patients in the hospital with breakthrough infections. But in general, breakthrough infections are not associated with the same complications you would get with a natural infection. This is why vaccination is so important—it really removes the ability of the virus to cause all those serious problems.

SOURCE: Amesh Adalja


If I get vaccinated, will I give my infant child an increased risk of getting sick from a COVID variant?

No. The best way to protect your infant (who's too young to be vaccinated) is for you to be vaccinated. That makes it much less likely that you will bring COVID-19—in any of its variant forms—into your household.

SOURCE: Amesh Adalja


Social Distancing and Other Public Health Measures

Why is the world’s response to COVID-19 so much greater than the response to other outbreaks like H1N1 or SARS?

One reason is that this virus is more easily transmitted than SARS (SARS caused an epidemic in 2003.). People with SARS were most likely to transmit the virus when they were quite ill, so a lot of transmission occurred in health care environments. Once we were able to improve infection control in health care environments, we were able to bring the epidemic under control. The 2009 pandemic caused by the new flu strain H1N1 was similar to COVID-19 in the sense that people transmitted their infections quite easily. But it was a milder virus; it didn’t produce the same level of severe illness or death that we so far have seen with this novel coronavirus.

COVID-19 is not as deadly as SARS was. On average, SARS killed about 10% of the known cases, and the estimates for this virus are much lower. But the fact that it’s so easily transmissible— much more like a flu than SARS—has made response to this pandemic quite difficult.

SOURCE: Jennifer Nuzzo

What metrics should communities be looking at to understand the real-time spread and anticipate the timing of the surge?

What’s going on at your local level can change over time, from week to week, or month to month.

Local or state health department websites can tell you what’s going on in your community. First, look at the number of COVID-19 cases. This number includes those who test positive—and, remember that not everyone who is infected or feels sick will access a test, so that number is just the tip of the iceberg. You want to see what that number of cases is doing over time, note if it is going up or down. Another thing to be aware of if there is major change is the amount of testing that’s going on in your community.

The second number to look at is the number of deaths in the community. There’s been a lot of debate about how to measure COVID-19 deaths, but you’re going to be looking at that trend over time. Not just how many people died today, but over the last week. Hopefully, it is decreasing, signaling lower risk.

This is a live public health moment. Things are changing all the time and no data is perfect, but a lot of data can be really helpful.

The Johns Hopkins Coronavirus map is a good resource to examine the spread in other states and countries around the world. The map is updated in real time as additional information is made available from a variety of sources.
You can also pay attention to the proportion of people in your community that are vaccinated.

SOURCE: Public Health On Call Podcast

For businesses that remain open, what are best practices to protect employees and customers?

The Center for Health Security has an Operational Toolkit for Businesses Considering Reopening or Expanding Operations in COVID-19. The toolkit includes an instruction manual, business risk worksheet, and an assessment calculator.

SOURCE: The Center for Health Security

Is temperature monitoring effective?

Taking temperatures is a very insensitive and imprecise tool. People can have elevated temperatures for all sorts of reasons that don’t correlate with illness, such as exercise. People can also suppress their fevers by taking Tylenol or other over-the-counter medications.

Having ubiquitous temperature monitors is not likely to be a great benefit and may result in a huge number of false positives and false negatives.

SOURCE: Eric Toner

What are the best ways to do contact tracing?

A great resource on contact tracing is the Johns Hopkins COVID-19 contact tracing course, which is available for free on Coursera. (If you have taken the course, check out this resource of Frequently Asked Questions about contact tracing jobs and opportunities.)

In the U.S., the commitment to contact tracing programs, to getting them to the scale and speed that we need, has really varied by state and by jurisdiction. It’s clear across the U.S. right now that very few places that have the programs, the interventions in place, to keep transmission under control. Contact tracing has to be part of that. But there are other interventions to reduce the number of contacts that people have every day to go along with it.

Contact tracing can only work if you can find cases, and we are still not there with testing in the U.S.

SOURCE: Emily Gurley

Are there effective contact tracing apps or tech platforms?

Contact tracing is critical to managing transmission, but it’s resource intensive and requires a lot of data gathering. This can strain public health departments and areas that can’t recruit or train tracers.

Digital tools can facilitate quick and effective communication and give access to real-time information. Contact tracing tools and apps can follow up with patients, notify individuals of potential exposure, and refer them to testing facilities and care if they develop symptoms. There are also apps that collect user-generated data where users report symptoms or fill out surveys that can help officials map outbreaks.

But these tools may be costly, and there are questions of usability of the platforms. There are also privacy considerations, as some apps require the use of Bluetooth and location sharing.

SOURCE: Smisha Argawal


Many communities are removing mask and social distancing mandates. What should families with unvaccinated children consider?

The virus is still with us and the pandemic is not over, particularly for families with young children and household members who are immune compromised. Consider a few key questions:

  • Whom will you be interacting with?
  • What is the current proportion vaccinated and the current spread of COVID-19 in my community?
  • Where will the interaction take place?
  • Is the interaction necessary and what are the policies in place?

SOURCE: Keri Althoff and Elizabeth Stuart


How should we be thinking about schools reopening?

The biggest factor determining risk in schools is what the virus is doing outside of them. In places where you have a very high test positivity, like well into the double digits, that suggests that the outbreak is very widespread and that testing isn't keeping up.

Regardless of whether schools open online, in person, or with a hybrid approach, there will be learning disruptions to consider. COVID-19 is exacerbating growing inequities around achievement, development, and graduation rates.

Schools can also expect a year of uncertainty and should think about plans for positive cases among students, faculty, and staff, or spikes in community transmission. Teachers and parents will need to help children manage distress caused by uncertainty, distance learning, and fear, and school leaders and educators will need to plan for different scenarios.

SOURCE: Johns Hopkins Bloomberg School of Public Health

How can schools develop a COVID-19 testing strategy?

Designing an effective testing strategy will require careful consideration of your group’s goals, resources, and structure. A testing strategy is a tailored plan that not only includes identifying the actual tests used but also describes the steps and factors to address to ensure that testing is rolled out in an effective way. In this section, we identify important factors you that can help you design your own testing strategy.

While a testing strategy will be unique to each organization, group, or individual, a few common factors should be considered when creating any testing plan:

  1. Are you trying to determine a current or past infection?
  2. Would you prefer to have samples collected at home or by a trained professional?
  3. How many people will be tested?
  4. What age groups will be tested?

SOURCE: The Center for Health Security's Testing Toolkit


How should we think about making sure communities of Color have equitable access to vaccines?

The coronavirus disease 2019 (COVID-19) pandemic has had tragic and disproportionate adverse effects on Black, Indigenous, and People of Color (BIPOC) communities across the United States. 

As the COVID-19 vaccination campaign begins, it is critical that vaccines be delivered fairly and equitably—so that everyone has the same level of access to this lifesaving technology. Just as pressing is the need to address longstanding disparities that have created the unequal situation that BIPOC communities are now in.

The Center for Health Security has released a plan for elected and appointed officials that contains the tools to create, implement, and support a vaccination campaign that works with BIPOC communities to remedy COVID-19 impacts, prevent even more health burdens, lay the foundation for unbiased healthcare delivery, and enable broader social change and durable community-level opportunities.

SOURCE: The Center for Health Security's Equity in Vaccination Plan

How should we think about the need for racial and ethnic diversity in clinical trials for COVID-19 vaccines?

It’s critically important that we have racial and ethnic diversity.

We know that COVID causes increased rates of severe disease in Latinx and Black populations and in Native American populations. We will certainly want to be able to offer these COVID vaccines to these high-risk populations and encourage their use. But we need to know how well these vaccines work in these populations—if different vaccines work differently—so that we can offer the most effective vaccines.

SOURCE: Ruth Karron

Why are Black and other communities of Color being hit especially hard by COVID-19?

Before COVID-19, minority communities were already disproportionately impacted by health inequities. People in those communities already have higher rates of obesity, diabetes, heart disease, and lung disease, so these are the folks who were actually going to be at more risk of getting seriously ill with COVID-19. These health inequities result from the financial stresses of being poor and the social stresses of being from a marginalized group with a history of institutionalized, sanctioned mistreatment by law enforcement and other societal institutions.

There’s a confluence of all these different factors—not having access to food, not having access to good quality housing, being crowded in small houses where there are multiple generations and unable to engage in social distancing or stock up on groceries for several weeks at a time, having to use public transportation, to work in essential jobs, and having less access to health care. These are all manifestations of structural racism.

SOURCE: Lisa Cooper

What can be done right now to reduce the toll of COVID-19 on Black and minority communities?

The biggest thing that can be done to protect Black and minority communities is to ensure equitable access to vaccines. 

Keeping an eye on the data is also an important priority: knowing who is impacted and where they’re impacted.

Communication is also really important—making sure that the public understands why we might be seeing these patterns, and that it’s more about our society and the way our resources and opportunities are allocated than it is about individual behaviors. We need to do what we can to better understand the challenges of those communities, engage with trusted leaders, listen with respect, and show empathy and concern. We need to recognize the remarkable contributions of African American communities and follow our words up with real actions that bring about positive change.

We also need to focus on frontline workers and low-wage workers, and understand their needs—providing protective equipment, safe spaces to work, paid sick leave, hazard pay, or health insurance and access to testing and care. And, we need to provide for people’s basic needs: stable housing, food security, and digital access to education and health care.

SOURCE: Lisa Cooper



What are good sources of information?

Are there books for people to learn more about the public health response to similar situations?

The Public Health Crisis Survival Guide is for anyone involved in a public health operational role who may have to think about how to manage a crisis and maintain credibility in the face of uncertainty. D.A. Henderson’s Smallpox, the Death of a Disease has great information about operational challenges to confronting the spread of disease and the goal of trying to reduce its impacts on society.

SOURCE: Jennifer Nuzzo

How can I learn more from experts? 

The Johns Hopkins Bloomberg School of Public Health hosts a daily podcast called Public Health On Call, featuring interviews with experts and others on the front lines.

You can also stay informed and up-to-date about COVID-19 and other urgent public health issues by subscribing to the Expert Insights Newsletter, which publishes on Tuesdays and Fridays.