EUA stands for Emergency Use Authorization, a mechanism the FDA uses to allow unapproved medical products to be used during a public health crisis. It applies to drugs, vaccines, diagnostic tests, and medical devices that haven’t gone through the full approval process but show enough promise to justify use when a serious or life-threatening threat exists and no adequate approved alternatives are available.
How an EUA Works
The legal authority for EUAs comes from Section 564 of the Federal Food, Drug, and Cosmetic Act. The process begins when the Secretary of Health and Human Services declares that circumstances justify emergency authorization, based on a determination of a threat or potential threat from chemical, biological, radiological, or nuclear agents. Once that declaration is in place, the FDA can authorize specific products for emergency use.
The FDA evaluates four criteria before issuing an EUA:
- Serious or life-threatening condition: The product must address a disease or condition that poses a genuine danger.
- Evidence of effectiveness: Available data must support, though not fully prove, that the product works for its intended use.
- Risk-benefit analysis: The known and potential benefits must outweigh the known and potential risks.
- No alternatives: There must be no adequate, approved, and available option already on the market.
That second criterion is where EUAs differ most from standard approval. The bar is “may be effective,” not “proven effective.” This allows faster access to treatments and diagnostics during emergencies, while still requiring meaningful scientific evidence.
EUA vs. Full FDA Approval
Full FDA approval for a drug or vaccine requires extensive clinical trials, often involving thousands of participants followed for one to two years. The agency reviews detailed data on manufacturing quality, long-term safety, and sustained effectiveness before granting approval through formal application pathways.
An EUA compresses that timeline dramatically. For the COVID-19 vaccines, the FDA required a median follow-up of at least two months from Phase 3 clinical trials, compared to the one-to-two-year follow-up recommended for full approval. The agency acknowledged that this shorter window was the minimum needed to have some confidence that protection wasn’t short-lived, but it left key questions unanswered: how long immunity would last, whether the vaccines prevented asymptomatic infection, and when boosters might be needed.
For context, a standard FDA review takes about 10 months. A Priority Review shortens that goal to 6 months. EUA reviews can happen in days or weeks when the urgency demands it, because the evidentiary standard is lower and the review is focused on the emergency use rather than permanent marketing.
What You’re Told Before Receiving an EUA Product
If you receive a product authorized under an EUA, the law requires that you be given specific information beforehand. Your healthcare provider must give you a Fact Sheet explaining that the product is not fully FDA-approved, that it has been authorized only for emergency use, and what the known and potential risks and benefits are. You must also be told about available alternatives, including clinical trials.
Critically, you have the right to accept or refuse an EUA product. This isn’t a formality. Providers are required to document that you received this information and were informed of your options. The intent is to make sure that the speed of an emergency authorization doesn’t bypass your ability to make an informed choice.
When EUAs Were Used Before COVID-19
EUA authority existed for nearly two decades before the pandemic made it a household term. Its most significant pre-COVID use came during the 2009 H1N1 swine flu pandemic, when the FDA authorized medical equipment and existing influenza drugs for expanded use. The authority was also used preemptively to authorize countermeasures in anticipation of MERS, Ebola, and Zika outbreaks, though none of those threats fully materialized in the United States. COVID-19 was the first time most Americans encountered the term, largely because the scale of EUA use was unprecedented: vaccines, antiviral treatments, monoclonal antibodies, and hundreds of diagnostic tests all entered the market through this pathway.
How EUAs End
An EUA is not permanent. There are two ways it stops being in effect: termination and revocation.
Termination happens at the declaration level. If the HHS Secretary terminates the underlying emergency declaration that supports EUAs, every authorization issued under that declaration ceases to be in effect. This is a broad action that can affect many products at once. Importantly, an EUA declaration is separate from a Public Health Emergency declaration, so EUAs can remain in place even after a public health emergency officially ends, as long as the EUA-specific declaration is still active.
Revocation targets a single product. The FDA can revoke an individual EUA if the circumstances that justified it no longer exist, the product no longer meets the criteria for authorization, or revocation is otherwise needed to protect public health. This might happen when an approved alternative becomes available or new safety data changes the risk-benefit balance.
Transitioning From EUA to Full Approval
For manufacturers, an EUA is a temporary status. If a company wants to keep selling its product after the emergency declaration ends, it needs to pursue standard FDA marketing authorization. The FDA has urged manufacturers to begin preparing those applications well before the EUA termination date, and recommends including a “Transition Implementation Plan” that addresses what happens to products already distributed, whether the full application is approved or denied.
If a manufacturer has submitted its application and the FDA hasn’t made a final decision by the time the EUA ends, the FDA generally allows continued distribution during the review period. This prevents a gap where a product people depend on suddenly disappears from the market while paperwork is being processed. The transition process has been especially relevant for COVID-19 diagnostic tests and medical devices, many of which entered the market exclusively through EUA pathways and now need to secure permanent authorization to remain available.