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Preventing Another “Tripledemic” with Vaccines for Flu, COVID, and RSV

Note: For the latest on COVID vaccines for fall 2023, please visit What to Know About the Updated COVID-19 Vaccine for Fall/Winter 2023

As fall approaches, pharmacies and doctor’s offices around the country will soon be displaying their signs reminding everyone to get their flu shot. Also available this fall: updated COVID-19 vaccines and a new RSV vaccine. To head off another “tripledemic” winter, enough people will need to get vaccinated at the right time.

In this Q&A, adapted from the July 31 episode of Public Health On Call, virologist Andrew Pekosz, PhD, a professor in Molecular Microbiology and Immunology, explains when flu, COVID, and RSV vaccines will roll out, who will benefit from them, and how effective they’re expected to be.

What do we know about the new COVID-19 vaccine?

The FDA voted to update the COVID vaccine to represent one of the variants that are collectively called XBB. There are a couple of different versions of XBB, but they are similar enough that antibodies to one recognize the other. The XBB-based vaccine for the fall will no longer be what we call a “bivalent booster,” which had two viruses in it; this will only have one (monovalent).

What’s not yet clear is what the CDC guidance and recommendations will be around how the vaccine should be used. Most likely it will be what we've seen before: recommended for people over the age of 60 for whom it’s been longer than four to six months since their last COVID vaccine. It will be available for other people, but it probably won’t be recommended for younger age groups.

When I as a virologist look at the data, if you haven't received a COVID vaccine in six months or a year, this is a good vaccine to take because it's very different from the variants that you’ve been immunized against before.

What about for people who have never gotten a COVID vaccine?

If you’ve never been vaccinated, the recommendation will still be to get the standard two doses, but it will be of the XBB vaccine, not the original ones. Then you'll have to get a third dose at some point later on to be considered fully vaccinated.

For children, however, the vaccine schedule is a little bit different. Your pediatrician will have all of the specific information on how to get the youngest children into the COVID-19 vaccination pool.

With surveillance of cases not as good as it once was, do we know which variants are currently circulating?

COVID-19 is still circulating, but case numbers have really gone down over the past six months, as have the corresponding deaths and hospitalizations. But we're still monitoring case numbers and sequencing cases to get a sense of what’s happening in the U.S. So we have a sense of what's going on, but it certainly isn't nearly as in-depth or as rapid as it was a year ago.

When will flu shots be available, and what are we going to see?

The flu vaccine should roll out at the end of August. The vaccine formulation was decided about six months ago, and the recommendations will be the same as they usually are: Everybody over the age of 6 months is recommended to get a flu vaccine. For younger kids, it's a two-shot schedule. For adults over the age of 12, it's one shot.

We're just starting to see data from the Southern Hemisphere, where it’s currently the middle of winter, and there seems to be a good amount of influenza activity there. All the different components of the vaccine are active in different countries. In the next month or so, we'll get a sense of how similar those viruses are to our vaccine and what we might expect for this coming flu season.

Last year’s flu season started pretty early. When should people get their flu vaccine this year?

September is a great time to get the flu vaccine. That September-October window is early enough so that if flu starts to emerge early—like it did last year at the end of October and into November—you still have a couple of weeks after your vaccine to build your immunity. And if flu emerges in December, January, or February, your vaccine immunity from September or October will still be helping you.

Do we know whether the flu virus strains in the vaccine seem to be lining up with illness?

Yes, all of the strains in the Northern Hemisphere vaccine are currently circulating in the Southern Hemisphere. More than likely, one or two of those strains will make it up to the Northern Hemisphere and start circulating here.

Do we have any defenses against Respiratory Syncytial Virus (RSV)?

RSV is a common pathogen that's seen in very young children. It also causes a lot of severe disease in individuals over the age of 60. Last year, we had a really large RSV outbreak that spanned the young and very old, and we didn't have any kind of treatments or vaccines for it. This year, we have an FDA-approved vaccine for RSV for people over the age of 60. The clinical trials look great in terms of its efficacy, and that will be rolling out this fall.

For kids up to 2 years old, there will be a new antibody treatment for RSV. That'll be available for lots of newborns, particularly ones in high-risk groups. It's an improved antibody treatment over the ones that were available in previous years. It will have a much longer half-life, and you'll only need one injection to protect children for about six months.

So at both ends of the age spectrum, we'll have much better tools to fight off RSV this year than we have in the past.

Why are we only now seeing a vaccine for RSV?

The RSV vaccine was in development even before the pandemic. In fact, the vaccines for COVID-19 were developed using that same technology as the RSV vaccines, which were really showing a lot of promise in clinical trials in 2019. The RSV vaccine got put on the backburner when COVID happened, and now, a few years later, they’ve finally approved the RSV vaccine that formed the basis for those successful COVID-19 vaccines.

Since RSV doesn’t mutate as much as COVID or flu, is this a one-time shot?

We hope that will be the case. What we haven't seen yet, though, is the effect of vaccine-induced immunity on how the virus will evolve. In the fall, we’ll be looking to see whether RSV infections are happening in vaccinated people or unvaccinated people, and whether the virus is changing if it does infect a vaccinated person.

RSV doesn't change nearly as much as the flu or COVID-19, so there probably won’t be a need to update the RSV vaccine on a regular basis. But if there were, that's not very challenging for manufacturers to do these days.

It has always been difficult to convince people to get the flu vaccine. How many people are actually getting their flu shot?

We're happy when we hit 50% of the population. But oftentimes, we don’t reach that.

There's been some reluctance to get COVID vaccines as well, and especially to get repeated vaccines. Are there concerns that people might ignore this new one?

Yes, and this is where we need to focus on the communication issue. As a scientist, I can point to the data that show these vaccines work, that they’re safe, and that, if used at a certain level, they can greatly benefit individuals' health and reduce stress on our health care system.

But the last couple of years of the pandemic have shown us that it's not enough to just have the data; you have to get that information to people in ways they can understand, and feel comfortable with. Just putting a message on the CDC website that says “get your vaccine because it works” doesn’t communicate effectively to a large swath of the population. We should be using social media in positive ways to get these messages across. 

These vaccines will make a really big difference this year—particularly the RSV vaccine—and we have to find effective ways to get people to understand that message clearly.

For a lot of vaccines, there's a mandated schedule for children and adolescents, but not for adults. So they’re seen as optional, and many people opt out. Is there any push to make these vaccines not so optional?

That's a tricky thing to balance. As public health investigators, we see the benefit of having that kind of mandated large-scale vaccination, but mandates make people a little more hesitant. It's about finding that sweet spot of making sure that the benefits are communicated clearly without making people feel like they're being forced to do something they don’t agree with.


Stephanie Desmon is the co-host of the Public Health On Call podcast. She is the director of public relations and marketing for the Johns Hopkins Center for Communication Programs, the largest center at the Johns Hopkins Bloomberg School of Public Health.