Are the vaccines safe?

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Are the new COVID-19 vaccines safe?

Andrew Badley, M.D., COVID-19 Research Task Force Chair, Mayo Clinic: The safety of these vaccines has been studied extensively. They've been tested now in about 75,000 patients in total, and the incidence of adverse effects is very, very low.

These vaccines were fast-tracked, but the parts that were fast-tracked were the paperwork; so the administrative approvals, the time to get the funding — those were all fast-tracked. Because these vaccines have such great interest, the time it took to enroll patients was very, very fast. The follow up was as thorough as it is for any vaccine, and we now have months of data on patients who received the vaccine or placebo, and we've compared the incidence of side effects between patients who received the vaccine and placebo, and that incidence of side effects, other than injection site reaction, is no different.

The side effects to the vaccines are very mild. Some of them are quite common. Those include injection site reactions, fevers, chills, and aches and pains. In a very, very small subset of patients — those patients who've had prior allergic reactions — some patients can experience allergic reaction to the vaccine. Right now we believe that number is exceedingly low.

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Key takeaways


Data must show that a COVID-19 vaccine is safe and effective before the Food and Drug Administration (FDA) can give emergency use authorization or approval. The safety of COVID-19 vaccines is closely monitored by the Centers for Disease Control and Prevention (CDC) and FDA.

The FDA has approved the Pfizer-BioNTech COVID-19 vaccine, now called Comirnaty, to prevent COVID-19 in people age 16 and older. The FDA approved Comirnaty after data found the vaccine is safe and effective.

Vaccines with emergency use authorization by the FDA include:

  • Pfizer-BioNTech COVID-19 vaccine for children ages 12 to 15
  • Moderna COVID-19 vaccine
  • Janssen/Johnson & Johnson COVID-19 vaccine