A: In a nutshell, both require a careful scientific review of the potential benefits and harms of a new medical product, but EUA’s are used to expedite this review in an emergency situation like a pandemic.
The full approval process for these vaccines will start when longer & more follow-up data from trial participants is available, and the manufacturers submit a Biologics Licensing Application (BLA).
The Emergency Use Authorization, or EUA process is used by the FDA to make medical products (including diagnostic tests, therapeutics, and vaccines) available quickly during an emergency based on the best available scientific evidence and taking into account that there are no other available approved alternatives.
During the COVID-19 pandemic, the FDA has made use of the EUA process to quickly make available to the public a number of diagnostic tests to enable rapid diagnosis of COVID-19, drugs that had shown preliminary efficacy for treatment of COVID-19, and over the past few months, three vaccines that are critical to controlling the pandemic.
To make a product available under EUA, the FDA reviews the potential benefit(s) of the product to the public against potential risks.
In the case of the three COVID-19 vaccines currently available in the US, studies provided enough scientific data about the manufacturing processes, safety profiles, and their ability to induce a robust immune response against a critical component of the SARS-CoV-2 virus.
Preliminary data from the Phase 3 efficacy trials, which involve administering either the vaccine or a placebo to thousands of trial volunteers, showed that they are on average very successful at protecting us from COVID-19.
These data allowed the FDA to determine that the three COVID-19 vaccines are acceptable in terms of their safety profile and have a lot of potential & immediate benefits to the public. Also, there are not alternatives that have been approved. FDA therefore issued EUA to all three.
Because of the urgent need for effective vaccines to combat the pandemic, efficacy data accumulated 2-4 months following completion of vaccination was reviewed by the FDA for the EUA’s. This process would generally take at least a couple of years.
The difference between ‘EUA’ and ‘FDA approved’ is the amount of data that the decision is based on. The manufacturers will need to file separately for FDA approval via a Biologics Licensing Application (BLA) when they have more and longer-term follow-up data from the vaccine recipients. When the FDA receives substantial evidence that the product is effective and that the benefits outweigh the risks when the product is used as recommended by the manufacturer, the FDA grants approval (‘FDA approved’).
This does not mean that the EUA process is any less stringent; it is made based on sound scientific data. It’s just not as large a dataset as would be submitted for a full FDA approval. Vaccine makers will continue to collect data from the Phase 3 trial volunteers, and the FDA evaluates safety and efficacy data in the general public even after COVID-19 vaccines are deployed under EUA. These data will be used to apply for FDA approval.
Based on the excellent safety profiles of these vaccines–both in the Phase 3 trials and after EUAs allowed them to be given to the public–we expect these vaccines to receive full FDA approval eventually.