What Are the Long-term Side Effects of COVID-19 Vaccine?

Dr. Paul Offit explains why COVID-19 vaccines would not be expected to cause long-term side effects.


What are the long-term side effects of COVID-19 vaccine?

Paul Offit, MD: Hi. My name is Paul Offit from the Vaccine Education Center. It is January 2021, and now in the midst of this pandemic, and now with the advent of two new vaccines, so-called messenger RNA vaccines to prevent SARS-CoV-2, people ask the reasonable question: Since this is a new strategy, a new way to make a vaccine, what are the long-term effects? How are we going to know about the long-term effects?

Well, vaccines like any medical product that have a positive effect can have a negative effect, and that's true here too. So for example, vaccines like the oral polio vaccine was a rare cause of polio; it occurred in maybe 1 per 2.4 million people, but it was real. Yellow fever vaccine was a rare cause of something that had the fancy name viscerotropic disease, which is really basically a form of yellow fever; again, occurred in about 1 in a million people; it was rare, but it was real. There was a squalene adjuvanted influenza vaccine that was used in Europe that was also a very rare cause of something called narcolepsy, which is a permanent disorder of wakefulness. And, measles-containing vaccine can cause a lowering of the platelet count, which can cause these sort of like broken blood vessels called petechiae; again, occurred in maybe 1 in 30,000 people — rare but real.

The good news about these terrible side effects is that they all occur within six weeks of a dose. That's why it is that the FDA, the Food and Drug Administration, insisted that each of these vaccines be studied for at least two months after the last dose, knowing that there's not been a serious side effect in history that hasn't occurred within weeks of getting the dose, within six weeks of getting the dose.

So, although some of those effects are long term like polio or narcolepsy, they're still picked up within six weeks. So I think in those preapproval studies where the vaccines have been tested in tens of thousands of people, you could say with confidence that there wasn't at least a relatively uncommon, serious side effect. And now that the vaccine has been given to more than 10 million people, I think you can say with some confidence that there doesn't appear to be right now a very rare, serious side effect that would be something that would cause a long-term problem. But again, we need to be humble, keep our eyes open and look what happens as we vaccinate hundreds and hundreds of millions of people to make sure that there's not an additional problem. But usually when those problems occur, they occur within six weeks of a dose.

Thank you.

Related Centers and Programs: Vaccine Education Center

Last Reviewed on Jan 28, 2021