By Dr. Mallika Marshall

BOSTON (CBS) — Dr. Mallika Marshall is answering your coronavirus vaccine-related medical questions. If you have a question, email her or message her on Facebook or Twitter.

We have a question from an anonymous viewer who writes, “I received the Moderna vaccine in March. When the Moderna booster becomes available, should I get the Moderna booster or the Pfizer booster? Does it matter?”

The Moderna vaccine is an excellent vaccine, so if I were you, I would probably stick with Moderna unless it’s not available to you at that time, in which case it should be fine to get the Pfizer vaccine. The FDA has decided mixing and matching COVID-19 vaccines is safe.

Sydney writes, “I am 100 years old. I am scheduled for a Pfizer booster but also want to get a flu shot. I know they can be given together, but I am concerned about side effects. Would waiting two weeks for the flu shot be prudent to possibly minimize side effects from the flu shot?”

Happy Birthday!!! I think you could go either way. If you tolerated the first two doses of the Pfizer vaccine well, then you could consider getting them together. And just because you’d be getting a COVID vaccine and the flu shot together does not mean you would experience double the side effects. But since we haven’t started to see the flu yet, it probably is also reasonable to get your booster now and wait a few days to get your flu vaccine. I wouldn’t wait any longer than that so you have plenty of time to build immunity to the flu before flu season begins.

Dr. Mallika is offering her best advice, but as always, consult your personal doctor before making any decisions about your personal health.

Dr. Mallika Marshall