Do I Need The Second Dose Of The Vaccine? Dr. Mallika Marshall Answers Your Questions

Dr. Mallika Marshall is answering your questions about the coronavirus vaccine.

Video Transcript

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- Well, there are a lot of questions tonight about that second dose of the COVID-19 vaccine. And Dr. Mallika Marshall has some answers. So Doctor, Marie writes, "I am hearing more and more of people getting very ill after their second vaccine. And I'm also hearing that the Moderna and Pfizer are over 90% effective after the first shot. So why put people through that kind of illness if the percentages are so high?"

MALLIKA MARSHALL: Yeah, Marie. So the early evidence does suggest that a single dose of the Pfizer vaccine, for example, is actually pretty effective. But we still believe that two doses is even more effective. So until we have further information, we really do want you to go and get that second dose.

And yeah. It's true that some people get more side effects after the second does, but when they do, they do tend to be mild. And usually go away within one to two days.

- Lynn says she's scheduled for her first dose this week. And she writes, "after I get my second dose, is it prudent to continue double masking with a medical mask when out in public or will a single cloth mask be sufficient?"

MALLIKA MARSHALL: You know, I really wouldn't change your behavior whether you're vaccinated or not. This is the advice I would give to the vaccinated and the not vaccinated. And that is you should consider wearing a double mask if you're going to be indoors or if you're going to be in a crowd or if you're going to be around other people who are not wearing masks.

If you're going to be outdoors and you can keep tons of space between you and other people, then you might get by with a single well-fitted mask. But err on the side of caution and double mask if you think it's necessary.

- All right. Mike has a question about traveling after the vaccine. He says, "I will be getting my second shot five days before I leave for Aruba. I need to be tested 72 hours before I leave. Is there a chance I could be sick from the shot and not be able to go?"

MALLIKA MARSHALL: Well, first of all, you would be safer to travel after you are fully vaccinated. But if you're going to travel, I just want you to know that getting vaccinated is not going to turn a COVID-19 test positive. So it's not like you would normally have a negative test, you get vaccinated, and all of a sudden, it turns positive. It will only be positive if you are infected with the coronavirus. So I just want to make sure it's clear out there that the vaccines cannot cause infection.

- That's a good distinction for people to understand. And one more question tonight, Doctor. Michael writes, "I will be getting the J&J vaccine and I'm scheduled for a cortisone shot in my left knee that day." So he wants to know if that's a problem.

MALLIKA MARSHALL: No. It shouldn't be a problem. And I think people-- I get a lot of questions about should I do this or that on the day that I'm getting vaccinated. I think perfectly fine if you're feeling good to go ahead and have routine medical and dental visits. What I wouldn't do is schedule appointments for the day or two after you get a vaccine because you might develop side effects. And you might feel a little pokey and perhaps not feel like going to those appointments.

- That's when you hear people might get a little fatigue. All right. Dr. Mallika Marshall, thank you so much. And Dr. Mallika offers her best advice, but as always, consult your personal doctor before making any decisions about your health. And if you have a question for her, here are the three ways to reach her.

Email [? Dr.Mallika@cbsboston.com, ?] on Twitter @mallikamarshall, or Facebook message her @DrMallikaMarshall. David.