Ask the Expert — Aron Sousa, M.D.

February 6, 2022

If we need boosters, does this mean the vaccines aren’t working?

No. The vaccines still work remarkably well. Just as natural immunity wanes months after infection with COVID, the immunity after vaccines tends to decrease over time. That is the same reason we have to repeat whooping cough (pertussis) vaccines periodically, because the immunity from the vaccine decreases over time.

Should I mix boosters (Pfizer-BioNTech and Moderna, and vice versa)?

You can, and it’s probably a good idea. When you get a booster that is different from your primary vaccine, your body makes a slightly different group of antibodies from the new vaccine. That creates added protection. It’s particularly true if you got Johnson & Johnson as your primary vaccine.

Can I get a flu shot and booster at the same time?

Yes, according to the CDC, you or others seeking the flu shot and the COVID-19 vaccine can get them during the same visit to your doctor’s office or pharmacy. That applies whether you’re getting your first dose of a COVID-19 vaccine, your second dose or a booster shot.?

Will we have to get a booster every year like we get flu shots?

We don’t know yet, but probably not. We get flu shots every year because the flu virus changes every year. Coronaviruses don’t have the same mechanism of changing their proteins as the influenza virus does. You might need to get periodic COVID boosters for the same reason we get pertussis or tetanus boosters, because of waning immunity, but probably not every year. We just don’t know yet.