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Q&A: Can You Get Flu and COVID Shot at the Same Time?

nurse holding syringe in front of girl

August 20, 2021 – With first-time COVID-19 immunizations continuing and the plan to offer booster vaccines to most Americans starting next month, what are the considerations for getting COVID-19 and flu shots at the same time?

Medscape/WebMD asked Andrew T. Pavia, MD, for his advice. He is the chief of the Division of Pediatric Infectious Diseases at the University of Utah, in Salt Lake City, Utah, and a fellow of the Infectious Diseases Society of America.

Q: With COVID-19 cases surging, is it a good idea to get the flu shot early this season?

Pavia: I don't think there is a rush to do it in August, but it is a good idea to get a flu shot this season. The consequences of getting the flu while COVID is circulating are serious.

Q: What are the implications?

Pavia: There are some we know and some we don't know. If you develop flu-like symptoms, you're going to have to get tested. You're going to have to stay home quite a bit longer if you get a definitive [positive COVID-19] test than you would simply with flu symptoms. Also, you're probably going to miss work when your workplace is very stressed or your children are stressed by having COVID circulating in schools.

The part we know less about are the implications of getting the flu and COVID together. There is some reason to believe if you get them together, the illness will be more severe. We are seeing that with RSV [respiratory syncytial virus] and parainfluenza and COVID coinfections in children. They appear to be quite severe.

"We don't know of any reason why you can't give the two shots together."

But for flu, we just don't have the data yet. That's because there really was no co-circulation of COVID and influenza with the exception of parts of China for a brief part of February and March.

Q: Will the planned administration of booster COVID-19 shots this fall affect the number of people who get the flu vaccine or how it's distributed?

Pavia: It creates a lot of logistical challenges, particularly for hospitals and other places that need to vaccinate a large number of their employees for flu and that will need to give COVID boosters at about the same time period. It also creates logistical challenges for doctors' offices.

But we don't know of any reason why you can't give the two shots together.

Q: Is it possible flu season will be more severe because we isolated and wore masks, etc, last winter? Any science behind that?

Pavia: The more you study flu, the less you can predict, and I've been studying flu for a long time. There are reasons that might suggest a severe flu season ― there has been limited immunity, and some people are not wearing masks effectively and they are gathering again. Those are things we believe protected us from influenza last season.

But we have not seen flu emerge yet. Normally we look to Australia, New Zealand, and South Africa during their winter ― which is our summer ― to get some idea of what is over the horizon for the Northern Hemisphere. Flu activity in Australia has been very modest this year.

That might mean flu may not show up for a while, but I would be loathe to make a prediction.

Q: What are the chances we'll see a flu outbreak like we're seeing with RSV, which is normally a winter illness?

Pavia: The fact that we had a summer RSV surge just gives you an idea of how the normal epidemiology of viral infections has been disrupted. It means anything could happen with influenza. It could show up late summer or fall or wait until next spring.

We really don't understand how those interactions work. When a new flu strain emerges, it often ignores the traditional behavior and shows up in the spring or fall. It happened in the 2009 pandemic, it happened in 1918.

The one thing I would safely predict about the next flu wave is that it will surprise us.

Q: Are you hopeful that combination vaccines in development from a number of companies, such as Moderna, Novavax, and Vivaldi, will be effective?

Pavia: It is beginning to look like COVID will be with us for the foreseeable future ― maybe as a seasonal virus or maybe as an ongoing pandemic. We are going to need to protect [ourselves] simultaneously against the flu and COVID. A single shot is a great way to do that ― nobody wants two needles; nobody wants two trips to get vaccinated.

An effective combination vaccine would be a really great tool.

We have to wait to see what the science shows us, because they are quite different viruses. We won't know if a combination vaccine works well and has acceptable side effects until we do those studies.

Q. Do you know at this point whether the side effects from two vaccines would be additive? Is there any way to predict that?

Pavia: There is no way to predict. There are so many things that go into whether someone has side effects that we don't understand. With fairly reactogenic vaccines like the mRNA vaccines, lots of people have no side effects whatsoever and others are really uncomfortable for 24 hours.

Flu is generally a better tolerated vaccine. There are still people who get muscle aches and very sore arms. I don't think we can predict if getting two will be additive or just the same as getting one vaccine.

Q: Other than convenience and the benefit for people who are needle-phobic, are there any other advantages of combining them into one shot?

Pavia: The logistics alone are enough to justify having one effective product if we can make one. It should reduce the overall cost of administration and reduce time off from work.

The combination vaccines given by pediatricians have been very successful. They reduce the number of needles for kids and make it much easier for parents and the pediatricians administering them. The same principle should apply to adults, who sometimes are less brave about needles than kids are.

Historically, combined vaccines in general have worked as well as vaccines given alone, but there have been exceptions. We just have to see what the products look like.

Q: For now, the flu vaccine and COVID-19 vaccine are single products. If you get them separately, is it better to put some time between the two?

Pavia: We don't know. There are studies that probably won't be out in time to decide in September. They are looking at whether you get an equivalent immune response if you give them together or apart.

For now, I would say the advantage of getting them together is if you do get side effects, you'll only get them once ― one day to suffer through them. Also, it's one trip to the doctor.

"I'm going to get my flu shot as soon as it's available. If I'm due for a COVID booster at that time, I would probably do them together."

The potential advantage of separating them is that is how we developed and tested the vaccines. If you do react to them, side effects could be milder, but it will be on two separate days.

I would recommend doing whatever works so that you get both vaccines in a timely manner.

I'm going to get my flu shot as soon as it's available. If I'm due for a COVID booster at that time, I would probably do them together.

Q: Do you foresee a point in the future when the predominant strain of SARS-CoV-2 will be one of the components of a flu vaccine, like we did in the past with H1N1, etc?

Pavia: It really remains to be seen...but it is very conceivable it could happen. The same companies that developed COVID-19 vaccines are working on flu vaccines.

Q: Any other advice for people concerned about getting immunized against both COVID-19 and influenza in the coming months?

Pavia: There is no side effect of the vaccine that begins to approach the risk you face from either disease. It's really one of the best things you can do to protect yourself is to get vaccinated.

In the case of flu, the vaccine is only modestly effective, but it still saves tens of thousands of lives each year. The SARS-CoV-2 vaccine is a much better vaccine and a deadlier disease.

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