This is an email from Your Coronavirus Update, a newsletter by Medium Coronavirus Blog.

The Latest: Your best resource for vaccine questions

Dear Reader,

The Medium Coronavirus Blog is on a holiday hiatus this week and next, and so I will be sending only one newsletter a week. Since vaccines are on everyone’s mind, I thought I’d take the opportunity to highlight some common questions and science-backed answers. It’s normal to have questions and, as always, the Blog is here to keep you up-to-date.

Be well,

Alexandra Sifferlin
Editor, Medium Coronavirus Blog

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These questions and answers come from science writer Tara Haelle’s extensive Covid-19 vaccine FAQ, and have been slightly edited for space. For more answers to your questions, check out the full guide.

This is one of the big questions researchers are trying to learn about the vaccines. Even if a vaccine prevents Covid-19 disease, it might still be possible for the virus to enter a vaccinated person, begin replicating, and then be passed on to someone else without the person ever knowing or developing symptoms. The pertussis (whooping cough) vaccine is a classic example of this phenomenon. Scientists don’t yet know if any of the Covid-19 vaccines prevent transmission, but all the trials include mechanisms to investigate whether they do.

Things will eventually get back to normal, but it will take more than a few months, and it will be gradual, explains [William Moss, MD, executive director of the International Vaccine Access Center]. “These vaccines are not going to be the silver bullet that brings us back to the pre-pandemic period. We’re still going to need, particularly in the months going forward, to continue to wear masks, socially distance, wash hands frequently, and avoid large gatherings. I think we’ll see over the course of 2021 a more phased return to our normal pre-pandemic life.”

It’s rare for a vaccine to have any side effects more than two weeks after getting it, but there are a few instances that have occurred with past vaccines. The 1976 swine flu vaccine had an increased risk of Guillain-Barré syndrome (GBS), a nerve disorder (one case per 100,000 people vaccinated). The seasonal flu vaccine has been linked to a small increased risk of GBS as well some years, but it’s in the neighborhood of one or two cases per million, and the risk of GBS from influenza infection is several times higher.

All of these longer-term, rarer side effects occurred within a few months of the vaccine and were picked up quickly by vaccine safety surveillance systems. Many of the mRNA trial participants have already been vaccinated for up to four months. No U.S.-approved vaccine has shown serious long-term effects more than a few months after vaccination, and it’s difficult to determine a biological reason that might happen. Companies needed at least two months of follow-up to apply for an EUA from the FDA, and by the time a vaccine is available for you, many more months will have passed when researchers gathered more data.

It’s valid and reasonable to have questions about possible long-term effects that occur several months after a Covid-19 vaccine, so researchers and regulatory officials are closely monitoring vaccine recipients to look for any. Continue to follow the news as the vaccines roll out to find out if any long-term effects get reported, but based on the history of vaccines in general, it’s not likely they will.

Read here for more Covid-19 vaccine Q&As.

Health and science journalist. Former editor of Medium’s Covid-19 Blog and deputy editor at Elemental. TIME Magazine writer before that