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Understanding the CDC’s Updated COVID Isolation Guidance

The updated recommendations align guidance for COVID infection with that for other common respiratory viruses.

Aliza Rosen

For the first time since 2021, the Centers for Disease Control and Prevention has updated its COVID isolation guidance.

Specifically, it has shifted the recommendation that someone who tests positive for COVID isolate for five days to a timeline based on the progression of the person’s symptoms. The update is part of a larger strategy to provide one set of recommendations for most common respiratory illnesses, including COVID, influenza, and respiratory syncytial virus (RSV).

In this Q&A, virologist Andy Pekosz, PhD, a professor in Molecular Microbiology and Immunology, explains the CDC’s new isolation guidance, the reasons for the update, and why the prevention and treatment strategies we’ve all become accustomed to still play an important part in reducing respiratory virus transmission.

What are the updated recommendations for someone who comes down with a respiratory infection?

The updated guidance from the CDC is to “stay home and away from others (including people you live with who are not sick) if you have respiratory virus symptoms that aren't better explained by another cause.” You can resume normal activities once your symptoms are improving and you’ve been fever-free—without the aid of fever-reducing medications—for at least 24 hours.

For the five days after you resume your normal activities, you should take extra precautions, like wearing a well-fitting mask and maintaining distance from others, gathering outdoors or in well-ventilated areas, cleaning hands and high-touch surfaces often, and testing when possible before gathering with others. If symptoms or fever return, you should start back at square one: staying home and away from others until you’ve been improving and fever-free for at least 24 hours.

What should you do if you’re at higher risk of severe illness?

If you’re at higher risk of severe illness—generally, this is older adults and young children, pregnant people, people with disabilities, and people with compromised immune systems—seek testing and contact your physician. If you test positive for COVID or flu, there are antiviral medications that can be taken within a few days of symptom onset and are extremely effective in reducing the likelihood that your symptoms become severe or that you need to be hospitalized.

How does this differ from previous guidance?

Before this, the CDC recommended that people who test positive for COVID should isolate away from others for five days and wear a well-fitting mask around others for the following five days. This was different from the general guidance for other common respiratory viruses, like flu and RSV.

Now there is no one-size-fits-all duration for how long to isolate; rather, you can resume regular activities—ideally still using other prevention strategies, like masking and distancing—based on when your symptoms have improved and your fever has gone away. 

This marks a significant change in guidance for people who test positive for COVID. Why has the guidance changed?

The CDC has simplified its recommendations for how long to stay home and isolate after testing positive or experiencing symptoms to be consistent across COVID-19, influenza, and RSV infections. This way, anyone who develops symptoms can follow the same isolation guidance, irrespective of what respiratory virus they’re infected with.

It’s important to note, though, that this guidance on how long to isolate is just one part of a larger strategy for combating respiratory viruses that includes:

  • Being up to date on recommended vaccines.
  • Practicing good hygiene regarding hand-washing, sneezing, and coughing.
  • Being aware of antiviral treatment options for COVID-19 and influenza.
  • Taking steps to improve indoor air quality.

If the guidance is the same for all respiratory viruses, is it still important to test to know what someone is sick with?

Yes, testing is still needed in order to get a prescription for antivirals to treat COVID-19 or influenza. Those antivirals have been shown to reduce disease severity in several different groups, so if you are in a high risk group, be sure to test early and contact your physician so you can get the antiviral prescriptions as soon as possible.

Testing can also play an important role in preventing transmission, particularly if you were recently around someone who has since become sick, or if you plan to spend time with someone who is at higher risk of severe infection.

For COVID in particular, rapid home antigen tests are a great way to determine whether you’re still infectious and able to infect others. Symptom severity can be fairly subjective and a presence or lack of symptoms does not always align with infectiousness, so testing out of isolation for COVID is still good practice if you have access to tests.

Does this new guidance mean that all of these respiratory viruses pose the same risk?

No, COVID-19 is still causing more cases and more severe disease than influenza or RSV. A person’s risk for severe infection will also vary based on a number of factors, including age and health conditions.

The updated guidance acknowledges that we can simplify the recommendations for what to do after becoming infected with a respiratory virus, as part of the larger strategy to address spread.

The CDC also recently recommended that people over age 65 receive an additional dose of this year’s COVID vaccine. What drove that decision?

There are a few reasons behind this new recommendation for older adults. First, most severe COVID infections are occurring in individuals 65 years and older who have not been vaccinated recently. The CDC’s recommendation notes that more than half of COVID hospitalizations between October 2023 and December 2023 occurred in adults over 65.

Second, we know immunity after vaccination wanes over a few months, so an additional dose will provide renewed protection through the spring. New COVID variants like JN.1 that are circulating now have some mutations that improve their ability to evade vaccine-induced immunity, but the antibodies made through vaccination still recognize them. It’s not a perfect match, but a second dose of this year’s vaccine will provide protection against current variants to an age group at increased risk of severe illness, hospitalization, and death.

When should people over 65 get this additional dose of the current COVID vaccine?

The recommendation from the CDC is for people 65 and older who have already received one dose of the 2023-24 COVID vaccine to get a second shot at least four months after their most recent dose.

For people in that age group who haven’t had the 2023-24 vaccine, there’s no need to wait. They can get their shot now to be protected through the spring.

Will there be an updated COVID-19 vaccine for these newer variants?

We can likely expect to see a new COVID-19 vaccine available this fall, just like we see new, updated influenza vaccines each fall. This spring—typically around May—a decision will be made on which variants the updated vaccine will be designed around, and like we saw in 2023, the new vaccine will be available in the fall as we head into the typical respiratory virus season.

Aliza Rosen is a digital content strategist in the Office of External Affairs at the Johns Hopkins Bloomberg School of Public Health.