ChristianaCare's Dr. Marci Drees answers more of your COVID-19 vaccine questions

PHILADELPHIA (WPVI) -- Dr. Marci Drees, chief infection prevention officer for ChristianaCare, is answering more of your COVID-19 vaccine questions.

Nikki from Pottstown asks: I saw a story about menstrual cycles changing after receiving a COVID vaccine. Should I be concerned about that if I am planning to become pregnant?

"It's been reported, anecdotally, women are saying my periods are heavier than usual for a couple of months, or some have said they are lighter than usual, the timing is off. So far, it's really been anecdotal. Now, there's a different myth going around about just infertility in general. That these vaccines can cause infertility and I just want to state again for the record, it's an absolute myth," Drees said.

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Tom from Wilmington asks: Are the first and second doses of the Pfizer and Moderna vaccines the same thing, or are there different substances in each shot?

"The difference between Pfizer and Moderna is minimal," Drees said. "They're both the same type of vaccine. They have some proprietary differences. So, if you get your two doses they should be from the same manufacturer, but it is the same vaccine you're getting with each shot."

Ken from West Chester asks: I am a COVID long-hauler and I am really scared about getting the vaccine. What should I do?

Drees says, get the shot.

"There haven't been any large studies yet, but there have been a couple smaller studies that look at people with long-haul symptoms who then get vaccinated and a significant portion seem to get better," she said.