With the widespread availability of COVID-19 vaccines in the months since EUA was granted, the available data on their safety, versus any risks, has ballooned.

Published: August 19, 2021

The differences between Food and Drug Administration (FDA) emergency use authorization (EUA) versus full approval for a vaccine mostly relate to the quantity of data from studies. Both processes by the FDA rely on data regarding a vaccine’s safety and effectiveness and require a conclusion that potential benefits outweigh any potential risks.

The FDA has been pursuing an “all hands on deck” approach toward approval for COVID-19 vaccines, Peter Marks, director of the FDA’s Center for Biologics Evaluation and Research, which regulates vaccines, told The Washington Post in July. Vaccine manufacturer Pfizer, which got an EUA for its COVID-19 vaccine in December, applied for FDA approval May 7, and Moderna made its application June 1.

Since then, FDA officials have been reviewing data and inspecting manufacturing facilities — two key and time-consuming parts of the standard approval process.

In the Washington Post article, the FDA official described the differences between EUA and FDA approval chiefly as differences of scale rather than scrutiny, with the agency undertaking review of vast amounts of data.

With the widespread availability of COVID-19 vaccines in the months since EUA was granted, the available data on their safety, versus any risks, has ballooned. In addition, clinical trial participants are followed for at least six months, also producing more data.

In addition, part of the full approval process for the FDA is a determination that the vaccine can be produced safely and reliably in the makers’ manufacturing facilities.

Any EUA can be granted if the FDA concludes that the “known and potential benefits outweigh the known and potential risks” of a product such as a vaccine. FDA approval merely requires the same conclusion, but has more data backing the conclusion.