The Food and Drug Administration (FDA) gave emergency use authorization for Pfizer’s COVID-19 vaccine on Dec. 11, 2020, for Moderna’s COVID-19 vaccine on Dec. 18, 2020, and for Johnson & Johnson’s vaccine on Feb. 27, 2021.

Additional vaccines are still under FDA review. This is a process the federal government uses during an emergency to authorize use of a vaccine, drug or medical device that is not yet licensed or that is licensed for a different purpose. Such treatments must undergo extensive testing and safety evaluation to receive an EUA.

Learn more about FDA Emergency Use Authorization »

Pfizer and Moderna vaccines

How they work

Safety data

Clinical trial data from both Pfizer and Moderna show an estimated 95% and 94.5% effective rate for these initial vaccines, respectively. The vaccine is the best defense against the virus and is an important step toward eradicating community spread. The Centers for Disease Control and Prevention (CDC) and FDA have a thorough and scientific process to evaluate vaccine safety before granting emergency use authorization. The clinical trials do show possible side effects that can include fever and body aches.

Learn more

  • Watch WashU Med and BJC virtual town hall recordings.
    • WashU Med town halls: Dec. 9, 2020 and Dec. 21, 2020: Efficacy, safety and rollout
    • BJC town hall, Jan. 26, 2021: New vaccine development, employee rollout, public rollout, safety, community engagement