Q&A: Flu Vaccine or COVID-19 Booster? Which Shot Should You Get First This Fall

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Experts say it is OK to get a flu shot and a COVID-19 booster at the same time, but it’s not necessary either. Victor Bordera/Stocksy
As the official start of autumn approaches, there are two important decisions to be made when it comes to vaccinations.
The first is when to get your annual influenza shot.
Experts say Australia is finishing up a flu season in which the illness started early and finished strong. They warn the United States could be in store for a similar pattern as our winter season draws near.
The second decision is when to get the new Omicron-specific COVID-19 booster shot that was authorizedTrusted Source by the Food and Drug Administration a few weeks ago.
The Pfizer and Moderna versions of that new booster are starting to arrive in pharmacies and other locations.
The recommendations to get both vaccinations may raise some questions for individuals.
Should you get both at the same time or space them out? Which one should you get first?
Healthline put these questions to two infectious disease experts.
Dr. Monica Gandhi, MPH, is a professor of medicine at the University of California San Francisco.
Dr. William Schaffner is a professor of preventive medicine at Vanderbilt University in Tennessee.
Should you get a flu shot and a COVID-19 Omicron booster at the same time?
Schaffner: You can receive both a flu shot and the updated COVID booster at the same time. Your immune response will be just as good as when the vaccines are given separately. Also, there is no increase in serious adverse reactions – although be mindful that you may experience two sore arms for a day or so.
Gandhi: The short answer is that we don’t have data on the simultaneous administration of the influenza vaccine and the new COVID-19 boosters. However, there was a study called the ComFluCov study performed in the United Kingdom on the concomitant administration of the older formulations of the COVID-19 vaccines with the seasonal flu shot… This study showed that administering both simultaneously did not lead to an increase in adverse effects and the increase in SARS-CoV-2 antibodies was not significantly different if the shots were spaced out or given at the same time. One limitation is that this study did not report on neutralizing antibody titers (which are really important) nor T cell immune responses to COVID-19 with the two different timings, but this U.K. study does give us some reassurance that – if easier for you logistically – you can go ahead and get the flu shot and the new COVID-19 booster at the same time.
If you get the shots at the same time, should you get them in the same arm?
Gandhi: The CDC advises that two vaccines given simultaneously be given at least one inch apart. However, given that some people have injection site reactions with both vaccines, I would recommend the shots be given in different arms. Again, there is no contraindication to giving them in the same arm except to have the injection site reactions minimized by having the two shots distributed.
Schaffner: If you are getting the flu vaccine and the COVID vaccine at the same time, most providers will give them in separate arms. It is possible to give both vaccines in the same arm, but the inoculation sites must be spaced at least an inch apart and that may present some difficulties, especially in smaller persons. That said, the substantial majority of both patients and healthcare providers prefer to give the two vaccines in separate arms when they are being received at the same time.
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What is the minimum amount of time you should have between the flu and COVID-19 inoculations?
Schaffner: If you decide to get the flu vaccine and the updated COVID booster on separate days, there is no required time interval between the two vaccines that you need to wait.
Gandhi: I think you can get the two shots at the same time per the COVID ComfluCov study we discussed above. However, I did want to discuss the minimum amount of timing between this new booster and your last booster for COVID-19 since we had a more frequent booster strategy in 2021 for COVID shots than the routine vaccine schedule for influenza. I would recommend at least 6 months from your last infection or booster before getting this Omicron-specific booster as I wrote in a piece in TIME (this may also have an influence on timing your booster with the flu vaccine). Recent research studiesTrusted Source during the Omicron variant era continue to demonstrate the benefit of an extended interval between doses in terms of increasing both neutralizing antibodies and memory B cells. A booster provides antibody protection for at least 6 months according to a recent study. Another study demonstrated that antibody levels stabilized 6 to 9 monthsTrusted Source post-vaccination for study participants both with and without previous infection. One of the aims of the Omicron-specific vaccines is to increase antibodies and prevent even mild infections. The antibody level plateau at the 6-month mark would thus signal an ideal time to boost with a BA.4/5-focused vaccine since a low pre-boost antibody level actually correlated with a greater fold increaseTrusted Source post-boosting.
Which vaccine should you get first? The flu shot or the COVID-19 booster?
Schaffner: It depends. The best time to get the flu vaccine is during October or the first two weeks of November. That will help assure that your protection will last throughout the flu season into March. If it has been several months since your last COVID vaccine dose, your protection is starting to wane, so getting your updated COVID booster might be first on your “to do” list. A reminder: it should be at least 2 months since your last dose of COVID vaccine or at least 3 months since you have recovered from COVID infection before you get the new updated COVID booster.
Gandhi: Now that we have discussed timing your COVID updated Omicron booster six months after your last booster (or infection), you can get the influenza vaccine first this fall if you are waiting until later fall-early winter for your COVID-19 booster. Otherwise, as we discussed above, data shows that it is fine to get them together.