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A Project of The Annenberg Public Policy Center
SciCheck’s COVID-19/Vaccination Project

How do we know vaccines are safe?

This article is available in both English and Español

No vaccine or medical product is 100% safe, but large randomized controlled trials, reviewed by multiple groups of experts, revealed no serious safety concerns and showed that the benefits outweigh the risks. 

As with any vaccine, safety is also being monitored as the shots are rolled out to members of the public to ensure there are no side effects of concern. A very small number of severe allergic reactions, for example — which are expected with any vaccine — have occurred with some of the authorized COVID-19 vaccines. For the COVID-19 vaccines, the CDC and FDA vaccine monitoring systems include a new smartphone-based tool called v-safe that allows enrollees to report any reactions to the vaccine.