COVID-19 vaccines need to work at least half of the time, FDA says

FDA expects that any COVID-19 vaccine it licenses should prevent the disease or decrease its severity in at least 50% of people vaccinated, according to guidance that the agency released today.

The recommendation, which FDA said reflects the advice the agency has provided vaccine developers in recent months, was part of an overall document called “Development and Licensure of Vaccines to Prevent COVID-19″ that provides a host of guidelines for vaccine developers.

The goal of the guidance is to ensure that the rush to produce a COVID-19 vaccine results in vaccines that are both safe and effective.

“While the FDA is committed to expediting this work, we will not cut corners in our decisions and are making clear through this guidance what data should be submitted to meet our regulatory standards. This is particularly important, as we know that some people are skeptical of vaccine development efforts,” said FDA Commissioner Dr. Stephen M. Hahn.

Dr. Peter Marks, director of the FDA’s Center for Biologics Evaluation and Research, added in the same news release that “FDA will only approve or make available a COVID-19 vaccine if we determine that it meets the high standards that people have come to expect of the agency.”

To provide perspective, two doses of MMR vaccine are 97% effective at preventing measles; one dose is about 93% effective, according to the Centers for Disease Control and Prevention. Two doses of inactivated polio vaccine (IPV) are 90% effective or more against polio. The flu vaccine, when it mostly matches the flu viruses in circulation for the season, can reduce the risk of flu illness by 40–60%.

Dr. Anthony Fauci, the director of the National Institute of Allergy and Infectious Diseases, told CNN on June 26 that he would settle for a COVID-19 vaccine that is 70–75% effective — though the U.S. population would still not achieve herd immunity if only, say, two-thirds of people received the vaccine.

Other guidelines included in the new FDA document include:

• There’s a need to include diverse populations in all phases of clinical development, including racial and ethnic minorities. The elderly and people with medical comorbidities should participate in late-phase trials.
• Studies should also provide data on use during pregnancy, as well as plan for assessing safety and effectiveness among children.
• Sizes of clinical trials must be large enough to demonstrate the safety and effectiveness of a vaccine.
• COVID-19 vaccines, as with any vaccine, will require post-approval safety monitoring using various existing surveillance systems. The FDA may also require post-marketing studies to further assess known or potential serious risks.