An Emergency Use Authorization (EUA) is a mechanism to facilitate the availability and use of medical countermeasures, including vaccines, during public health emergencies, such as the current COVID-19 pandemic. Under an EUA, the FDA may allow the use of unapproved medical products, or unapproved uses of approved medical products in an emergency to diagnose, treat, or prevent serious or life-threatening diseases or conditions when certain statutory criteria have been met, including that there are no adequate, approved, and available alternatives. Taking into consideration input from the FDA, manufacturers decide whether and when to submit an EUA request to the FDA.
Once submitted, the FDA will evaluate an EUA request and determine whether the relevant statutory criteria are met, taking into account the totality of the scientific evidence about the vaccine that is available to the FDA.
For an EUA to be issued for a vaccine, for which there is adequate manufacturing information to ensure quality and consistency, the FDA must determine that the known and potential benefits outweigh the known and potential risks of the vaccine. An EUA request for a COVID-19 vaccine can be submitted to the FDA based on a final analysis of a Phase 3 clinical efficacy trial or an interim analysis of such trial, i.e., an analysis performed before the planned end of the trial once the data have met the pre-specified success criteria for the study’s primary efficacy endpoint.
From a safety perspective, the FDA expects an EUA submission will include all safety data accumulated from Phase 1 and 2 studies conducted with the vaccine, with an expectation that Phase 3 data will include a median follow-up of at least two-months (meaning that at least half of vaccine recipients in Phase 3 clinical trials have at least two months of follow-up) after completion of the full vaccination regimen. In addition, the FDA expects that an EUA request will include a Phase 3 safety database of well over 3,000 vaccine recipients, representing a high proportion of participants enrolled in the Phase 3 study, who have been followed for serious adverse events and adverse events of special interest for at least one month after completion of the full vaccination regimen.
Part of the FDA’s evaluation of an EUA request for a COVID-19 vaccine includes evaluation of the chemistry, manufacturing, and controls information for the vaccine. Sufficient data should be submitted to ensure the quality and consistency of the vaccine product. The FDA will use all available tools and information, including records reviews, site visits, and previous compliance history, to assess compliance with current good manufacturing practices.
You can find out more about EUAs and COVID-19 vaccines here.