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FDA Will Require 2 Months of Safety Data Before Approving a COVID-19 Vaccine

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Key Takeaways

  • The Food and Drug Administration (FDA) will require vaccine manufacturers to provide two months of safety data before it will approve a COVID-19 vaccine for use by the general public.
  • The FDA believes the two-month period will allow time enough for possible side effects or adverse outcomes of a potential vaccine to appear.

On October 6, the Food and Drug Administration (FDA) announced that it will require COVID-19 vaccine manufacturers to share two months of safety data before it will approve a vaccine for use by the general public. The FDA's decision comes as there is growing public distrust of a future COVID vaccine’s safety.

The FDA's New Requirements

Under the FDA's new requirements, there will need to be two months of follow-up data on the health of clinical trial volunteers after they receive their second doses of the vaccine. The FDA may choose to grant a vaccine maker an emergency use authorization—a designation that allows for public use of a product—if the new requirements are met.

Shobha Swaminathan, MD

Safety is critical at the heart of making sure that people trust the work that we’re doing.

— Shobha Swaminathan, MD

The FDA explained in its guidelines that it wants to see data from Phase 3 trials when participants have completed the full vaccine regimen, and for two months after. The FDA believes that this timeline will provide "adequate information to assess a vaccine's benefit-risk profile."

According to the guidelines, the FDA will be looking at "adverse events; cases of severe COVID-19 disease among study subjects; and cases of COVID-19 occurring during the timeframe when adaptive (rather than innate) and memory immune responses to the vaccine would be responsible for a protective effect."

The FDA also says that there needs to be “sufficient cases of severe COVID-19 among study subjects” to prove that there is a low risk of people developing serious complications from the vaccine.

Additionally, the FDA expects manufacturers to demonstrate data related to certain syndromes—specifically, vaccine-associated enhanced respiratory disease (ERD) from the vaccine. “A total of five or more severe COVID-19 cases in the placebo group would generally be sufficient to assess whether the severe COVID-19 case split between vaccine vs. placebo groups supports a favorable benefit-risk profile or conversely raises a concern."

There are currently 11 vaccines in Phase 3 (the final phase) of clinical trials. However, several of the trials conducted by several major pharmaceutical companies have recently been paused after at least one study participant developed a serious, unexplained illness.

The Case for a 2-Month Wait

“I think it’s great that the FDA is demanding that we have two months of safety data,” infectious disease expert Shobha Swaminathan, MD, an associate professor and the principal investigator for the Moderna COVID-19 vaccine trial at the Rutgers New Jersey Medical School Clinical Research Center, tells Verywell. “Safety is critical at the heart of making sure that people trust the work that we’re doing.”

Swaminathan explains that the most common side effects from vaccines occur within a two-month timeframe. “Most vaccine side effects, such as fever, fatigue, and injection site reactions occur over the first week, and more complex ones can occur over six weeks. That’s why a minimum of two months is helpful to detect what may be occurring.”

Shobha Swaminathan, MD

Don’t jump to conclusions about the scientific process. There’s a lot of misinformation out there.

— Shobha Swaminathan, MD

Swaminathan says that the timeframe is “trying to balance public need without compromising safety." She hopes that the FDA's guidance will help change public perception of the vaccine development process.

“There is the perception in the public that COVID-19 vaccine research is being rushed ahead of schedule, and some people are worried that it is coming at the cost of safety measures, which is actually not true," says Swaminathan. "The FDA will make a determination if the safety information they have [from researchers] is adequate.”

Overall, Swaminathan urges people to trust the process. “Don’t jump to conclusions about the scientific process. There’s a lot of misinformation out there.”

What This Means For You

The FDA’s requirement for two months of follow-up data after people receive a COVID-19 vaccine should help ensure that any potential side effects are caught before the vaccine is available to the general public. However, the process might ultimately take longer.

The public should trust that the vaccine development and approval process is safe and that the FDA will not approve a vaccine until it is ready—and safe.

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  1. U.S. Food & Drug Administration. Emergency use authorization for vaccines to prevent COVID-19: guidance for industry. Updated October 2020.

  2. Food and Drug Administration (FDA). Development and licensure of vaccines to prevent COVID-19. Updated June 2020.

  3. Corum J, Wee SL, Zimmer C. Coronavirus vaccine trackerThe New York Times. Updated October 16, 2020.