By Dr. Mallika Marshall

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

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

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“I volunteer at a local nursing home and they test for the virus often. There have been two cases among employees. Should I still volunteer?” -Irene

I think you can consider volunteering if you’re generally healthy, have been fully vaccinated and boosted (if eligible), and if you and the people in the nursing home wear masks at all times when in close proximity.

“Our eldest grandchild who is 21 and rarely goes out but will not get vaccinated and the youngest who is 3 years old and in preschool cannot get the vaccine. If we meet with the family to exchange Christmas gifts indoors, who is more likely to be a danger to us?” -Penny

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Gosh, that’s hard to know. Hopefully, the three-year-old is masked at school and is surrounded by adults who are fully vaccinated. Obviously, it’s not ideal to be in mixed company (vaccinated and unvaccinated), unmasked, and indoors. But if you must all gather together for Christmas, it might give you some peace of mind to have everyone do a rapid home antigen test on the morning of your celebration. If everyone tests negative, it’s less likely that anyone will transmit the virus to others that day.

“I got two Moderna vaccines last winter and a Moderna booster in August. I just got another booster last month. Do you think I’m in trouble or maybe overdosed?” -Everett

While that is not advised, you can’t really “overdose” on the vaccine. I’m assuming that you feel fine and didn’t have significant side effects. But getting another booster so close to your first, assuming you’re not immunocompromised, probably didn’t provide much-added benefit.

“I’ve received both my Moderna primary and booster shots. Is it true that I can still get Covid and transmit it to others?” -Rich from Plymouth

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Vaccinated people are much less likely to get infected in the first place. But if they do get a breakthrough infection, they can transmit the virus to others, but we’re not sure to what degree. That’s why it’s still important for vaccinated people to be cautious until we know more and until we drive cases further down. However, the spike in cases we’re seeing nationwide is predominantly due to unvaccinated people getting infected and passing it on to other unvaccinated people.

Dr. Mallika Marshall