Vaccine Blogs

FAQ: Emergency Use Authorizations (EUAs) and COVID-19 Vaccines

The views and opinions expressed here are those of the authors and do not necessarily reflect the position of either Johns Hopkins University and Medicine or the University of Washington.

Jessica E. Atwell, Infectious Disease Epidemiologist
Ruth A. Karron, Pediatrician, Respiratory Virologist, and Vaccinologist
December 9, 2020

Key points:

  • Two vaccines – the Pfizer/BioNTech mRNA vaccine and the Moderna mRNA vaccine – will be reviewed for Emergency Use Authorization (EUA) by the FDA in December 2020.
  • An EUA is not FDA approval, but it permits the use of a product during a public health emergency.
  • EUAs are not new, and are not just for vaccines – but the FDA has issued specific guidance for EUAs for COVID-19 vaccines.

What is an Emergency Use Authorization, or EUA?
An Emergency Use Authorization (EUA) allows the U.S. Food and Drug Administration (FDA) to make a product or drug – whether new or not yet proven for a given use – available during an emergency, provided there are data to suggest that it is reasonably safe and effective. The basic requirements for an EUA are:

  1. a public health threat exists;
  2. there is reason to believe that the product will be effective in diagnosing, preventing, or treating the illness;
  3. the known or potential benefits outweigh the risks; and
  4. there are no adequate, approved, available alternatives.1

How did EUAs come to be? What was the first EUA?
The authority to grant EUAs dates back to federal laws passed in 1938 and the Project BioShield Act of 2004, which was part of bioterrorism preparedness activities following 9/11. The first EUAs for the civilian population were granted in response to pandemic influenza in 2009, including an EUA for the use of oseltamivir (Tamiflu) in infants.2

Have EUAs been issued for products to treat or prevent COVID-19?
The FDA has granted EUAs for a number of diagnostic tests for COVID-19, personal protective equipment, medical devices, drugs (e.g., remdesivir), and biological products (e.g., convalescent plasma).3

Have there been EUAs for vaccines before?
An EUA was issued for anthrax vaccine in 2005. If EUAs are granted for the Pfizer/BioNTech and Moderna COVID-19 vaccines, these will be the first EUAs issued for vaccines for civilian populations.

Are there additional requirements for COVID-19 vaccine EUAs?
Yes, the FDA released specific guidance in October 2020 on the EUA process for COVID-19 vaccines. The FDA specified a minimum vaccine efficacy of 50%, which is substantially exceed by both the Pfizer/BioNTech and the Moderna COVID-19 mRNA vaccines. In addition, the FDA specified a minimum period of safety follow-up before EUA submission, and that companies must provide plans for continued safety follow-up. The FDA also requires that vaccine companies provide data on the production of the vaccine, including the manufacturing process and quality controls, and the supply chain.4

What is the process for reviewing applications for COVID-19 vaccine EUAs?
Applications for both the Pfizer/BioNTech and Moderna vaccines were submitted to the FDA, which has had an opportunity to review and analyze the data provided by the companies. This information will be made publicly available. The Vaccines and Related Biological Products Advisory Committee (VRBPAC), an independent group of scientists, will review the data and make recommendations to the FDA about issuing EUAs for these vaccines. The Vaccines and Related Biological Products Advisory Committee (VRBPAC) review of the Pfizer/BioNTech vaccine will occur on December 10th and of the Moderna vaccine on December 17th. These discussions will be live-streamed here and open to the public.

If an EUA is issued, is it the same as FDA approval? Does it mean that the vaccine trials end?
An EUA is not a license. The vaccine trials will continue in order to learn as much as possible about the long-term safety and efficacy of the Covid-19 vaccines. This information could be used to support future applications to the FDA to license the vaccines.


Jessica E. Atwell, Infectious Disease Epidemiologist

Jessica E. Atwell, PhD MPH is an Infectious Disease Epidemiologist in the Department of International Health at the Johns Hopkins Bloomberg School of Public Health. She works with both the Center for Immunization Research and the Center for American Indian Health, and focuses on the prevention of respiratory viral infections, as well as vaccine development, access, and uptake. Since early 2020, she has been working extensively on the public health response to COVID-19 and understanding the epidemiology of SARS-CoV-2 in American Indian and Alaska Native communities.

Ruth A. Karron, Pediatrician, Respiratory Virologist, and Vaccinologist

Ruth A. Karron, M.D., is a pediatrician, respiratory virologist, and vaccinologist. She is a Professor in the Department of International Health, Director of the Center for Immunization Research, and Founding Director of the Johns Hopkins Vaccine Initiative. She is a former member and chair of VRBPAC.