How do clinical trials work?... - National Cancer Institute

Did you know? Before the U.S. Food and Drug Administration (FDA) approves or authorizes a vaccine, the vaccine goes through rigorous clinical trials to make sure it works well. Once trial results are reviewed, FDA can decide whether to approve a vaccine or authorize it for emergency use in the United States. After FDA approves a vaccine or authorizes a vaccine for emergency use, CDC and other federal partners assess COVID-19 vaccine effectiveness under real-world conditions. Learn more: https://