FDA Emergency Use Authorization (EUA)

Understanding the process, requirements, and legal framework for emergency vaccine authorizations.

What Is an EUA?

An Emergency Use Authorization (EUA) is a mechanism that allows the FDA to authorize the use of an unapproved medical product — or an unapproved use of an approved product — during a declared public health emergency. EUAs are not the same as full FDA approval.

EUAs allow faster access to medical countermeasures when there is no adequate approved alternative and when the known and potential benefits outweigh the known and potential risks. The FDA may revoke an EUA at any time.

EUA vs. Full FDA Approval

Standard of Evidence

Full approval requires substantial evidence of safety and effectiveness from adequate and well-controlled clinical trials. EUA requires that available evidence suggests the benefits outweigh the risks — a lower but still significant evidentiary bar.

Data Requirements

Full approval typically requires at least 6 months of safety follow-up data and complete clinical trial results. EUA can be granted with shorter follow-up and may be based on interim trial data.

Post-Market Requirements

Full approval includes standard post-market surveillance requirements. EUAs typically include additional conditions — such as mandatory safety reporting, distribution controls, and fact sheet requirements.

Duration

Full approval is indefinite (subject to ongoing safety monitoring). EUAs are tied to the declared emergency and may be revoked when the emergency ends or when the product receives full approval.

The EUA Process

Emergency Declaration

An EUA requires a declaration of emergency by the HHS Secretary. The declaration defines the scope of the emergency and the countermeasures that may be authorized.

Sponsor Submission

The manufacturer submits an EUA request to the FDA including all available safety, efficacy, and manufacturing data. There is no minimum data requirement — the FDA evaluates whatever is available.

FDA Review

FDA scientists conduct an independent review of all submitted data. For COVID-19 vaccines, the FDA also convened its independent Vaccines and Related Biological Products Advisory Committee (VRBPAC) for public review before issuing each EUA.

Authorization & Conditions

If granted, the FDA issues an EUA letter specifying authorized use, required labeling (Fact Sheets), distribution conditions, and ongoing reporting requirements.

COVID-19 Vaccine EUAs

The COVID-19 pandemic produced the most visible use of vaccine EUAs in U.S. history:

Pfizer-BioNTech (December 11, 2020)

First COVID-19 vaccine EUA, initially for ages 16+. Subsequently expanded to younger age groups and received full FDA approval (Comirnaty) on August 23, 2021 for ages 16+.

Moderna (December 18, 2020)

EUA for ages 18+. Received full approval (Spikevax) on January 31, 2022.

Janssen/J&J (February 27, 2021)

Single-dose EUA. Later restricted due to rare thrombosis-with-thrombocytopenia syndrome (TTS) signal. EUA maintained for certain populations.

Informed Consent Under EUA

EUA products carry specific informed consent requirements:

Under 21 U.S.C. § 360bbb-3(e)(1)(A)(ii), recipients of EUA-authorized products must be informed of:

The fact that the product is authorized under EUA (not fully approved)
The known and potential benefits and risks
The extent to which such benefits and risks are unknown
That they have the option to accept or refuse the product
Any available alternatives

This informed consent requirement was central to legal challenges to COVID-19 vaccine mandates for EUA-authorized products.

Sources & Citations

•FDA. "Emergency Use Authorization." fda.gov/emergency-preparedness-and-response/mcm-legal-regulatory-and-policy-framework/emergency-use-authorization, 2023.
•21 U.S.C. § 360bbb-3 (Federal Food, Drug, and Cosmetic Act, Section 564).
•FDA. "COVID-19 Vaccines." fda.gov/covid19vaccines, 2023.
•Krause PR et al. "Considerations in boosting COVID-19 vaccine immune responses." The Lancet, 2021.

Regulatory