Emergency Use Authorization vs. Full Approval: What are the Implications?

EUAs can enable people to get immediate access to preventive therapy or treatment, but is it always worth aiming for full approval?

Emergency use authorizations, or EUAs, have gotten a lot of attention during the COVID-19 pandemic. The concept of the U.S. Food and Drug Association (FDA) authorizing a product or treatment quickly and without going through a full and complete review process was first introduced in 2005. At that time, the FDA issued an EUA for an anthrax vaccine available to military personnel due to a spate of anthrax-laced letters that killed or sickened nearly 2 dozen people.

Over the following years, EUAs were issued for a variety of experimental therapies for diseases such as H1N1 (swine flu), Middle East Respiratory Syndrome (MERS), Ebola, and Zika, which often arose quickly and threatened to become bona fide pandemics. Since last year, numerous EUAs have been issued for COVID-19-related products, including diagnostic and antibody tests, clinical treatments, and vaccines.

But what does it actually mean when a product is given an EUA, and why don’t companies automatically seek full FDA approval? According to Diana Zuckerman, PhD, president of the National Center for Health Research, there are several reasons why a company might not pursue approval for a product.

“One [reason] is that it’s found to not work, and so no effort is made to get it approved, and the other is that the company doesn’t necessarily have the incentive to do the research that they would need to do in order to get it approved, because the standards for an EUA are always lower than the standards would be for FDA approval,” she said. “If FDA approval would require a bigger, longer-term study with more patients, that just may not be worth it.” She offered the example of EUAs for various therapies for the Ebola virus, which does not currently present a threat to the US.

Even if a company wants to receive full approval for a product, it can run into problems if it can’t find enough of a patient population to participate in large-scale trials, added Susan Wood, PhD, professor of Health Policy and of Environmental and Occupational Health at the George Washington University Milken Institute School of Public Health and the former Assistant Commissioner for Women’s Health at the FDA.

Zuckerman and Wood agreed that, ideally, companies producing therapies that receive EUAs would go on to pursue approval for these therapies, especially as approved therapies can sometimes be repurposed to work for conditions other than those for which they were initially intended. “The reason why we were able to move...quickly with Covid was because of the work that had been done with other coronaviruses previously, and that really set the stage,” Zuckerman said. “Whether it’s for a rare disease or a future pandemic that we can’t predict, yes, having more information now can help us later.”

For companies, having full approval provides a measure of control. The FDA can withdraw an EUA at any time, preventing a company from selling or dispensing their product; in contrast, it can take several years for the agency to rescind an approval. Insurance typically doesn’t pay for products under an EUA, although in the case of Covid-19 vaccines the government is footing the bill, possibly making financial motives less of a factor for pharmaceutical companies.

But while EUAs are designed to help people get immediate assistance, it’s not uncommon for tests or therapies granted EUAs to end up being ineffective. In the case of COVID-19 tests and treatments, the FDA issued EUAs it later revoked. For example, in March of 2020, companies were permitted to sell antibody tests—which purported to tell users whether or not they had COVID-19 in the past—without submitting EUA applications. In May of 2020, companies were allowed to sell COVID-19 diagnostic tests for 15 business days before they had to submit EUA applications. During that month, the FDA issued 84 EUAs for various labs and companies, and there were an additional 400 applications pending review.

But by February of 2021, enough data on testing had been collected for the FDA to reject 225 different antibody tests. Similarly, although the FDA had granted EUA status to the drug hydroxychloroquine in March of 2020, by June of 2020 it was clear from studies that the drug not only had no discernible benefit but might even be harmful to Covid-19 patients, and the EUA was withdrawn in June 2020.

The lack of full approval by the FDA has been cited as a factor in the reluctance of some people to get the Covid-19 vaccine and has emerged as a flashpoint in the fight over vaccine mandates. Typically, mandates come after years of experience with a vaccine. “Normally...the testing is slower, the back and forth between the FDA and companies is slower, the review process is slower, and it comes on the market in a graduated fashion,” Wood said. At that point, there’s much more acceptance by the general population. “Now, everything’s been compressed, including EUA, and we’re moving straight into mandates by businesses.”