By Dr. Mallika Marshall

BOSTON (CBS) – Dr. Mallika Marshall is answering your coronavirus-related medical questions. If you have a question for Dr. Mallika, 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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Ron writes, “I had a Moderna shot in Florida a week ago and have had a headache ever since. I wonder how long it will last. I wonder whether or not I’m guaranteed of having it worse with the second round.”

It’s very common to have a headache after the vaccine and while most side effects resolve in 36 hours, some people have a headache for a few days. I know I did. Your headache also could be due to something else. You may get a headache after the second shot as well, or you may get different side effects. That said, if your headache is “the worst headache of your life” or you have other concerning symptoms like changes in vision, vomiting, or numbness or weakness in a part of your body, get medical attention right away.

Another viewer says, “I made an appointment to get the Pfizer vaccine next week. However, my sister received an email from a friend who claims that the Pfizer vaccine can cause heart failure and sudden death. Should I have the Moderna vaccine instead?”

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I’m not sure where your sister’s friend got his information, but this is not true. In fact, the CDC just recently announced that there have been no serious safety problems identified with either the Pfizer or Moderna vaccines. I would not hesitate to get either one.

Connie writes, “My husband and I are 78 and have two granddaughters. We wonder as we approach having our 2nd shot if we should expand to taking them in the car and hugging them.”

You will be considered fully vaccinated once you’re 2 weeks out from your second dose, which is wonderful. That said, the vaccines, while highly effective, are not 100% effective and we don’t know if they can prevent you from passing the virus on to others. So, I would say, use your judgment. Hugging your grandchildren will not be risk-free for them or for you, but it may be a risk you’re all willing to take. As always, contact your doctor for his/her advice.

Sue in Salem writes, “In the mad rush how do spouses get vaccinated together. What a nightmare! I feel like just staying home!” Joan who lives on the Cape and Steve who lives in Rockport wonder the same thing.

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I completely understand why couples would want to get appointments at the same time, but until there is more flexibility in appointment times, that may be hard to do. If you want a vaccine sooner rather than later, you may have to schedule appointments days apart. Otherwise, you may have to wait until availability opens up in the next few weeks.

Dr. Mallika Marshall