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A Project of The Annenberg Public Policy Center

Why were the COVID-19 vaccines authorized on an emergency basis, and how is that different from full approval?

This article is available in both English and Español

The Food and Drug Administration expedited review of the vaccines because of the public health risks of the ongoing pandemic. All three vaccines in use in the U.S. were rolled out under an emergency use authorization, or EUA, which is typically less stringent than the full licensure, which is called a biologics license application, or BLA. However, the FDA added more rigorous requirements for a COVID-19 vaccine EUA.

Under a standard EUA, regulators must determine that the product “may be effective” and the “known and potential benefits outweigh the known and potential risks.” For these EUAs, the FDA went further and required “at least one well-designed Phase 3 clinical trial that demonstrates the vaccine’s safety and efficacy in a clear and compelling manner.” The agency also wanted to see at least two months of follow-up data on half or more of the participants, and said it expected vaccine companies to continue to collect data to pursue full approval.

The FDA granted full approval to the Pfizer/BioNTech COVID-19 vaccine for people 16 years of age and older on Aug. 23, 2021. The decision was based on additional data from the phase 3 clinical trials, in which more than half of participants were followed for at least four months after receiving a second dose, and a review of safety surveillance and manufacturing data, including inspections of production facilities. After a similar review, the agency fully approved the Moderna vaccine for people 18 years of age and older on Jan. 31, 2022.