FDA authorizes additional booster of Pfizer-BioNTech, Moderna Covid-19 vaccine for adults 50 and older

The Food and Drug Administration on Tuesday authorized a second booster of Pfizer-BioNTech and Moderna for adults 50 years and older, announcing that a fourth shot improves protection against severe Covid-19.

The agency also authorized a second Pfizer-BioNTech booster for immunocompromised children older than 12 and a second Moderna booster for immunocompromised adults over 18 years old.

“Current evidence suggests some waning of protection over time against serious outcomes from Covid-19 in older and immunocompromised individuals," said Peter Marks, director of the FDA’s Center for Biologics Evaluation and Research, in a statement. "Based on an analysis of emerging data, a second booster dose of either the Pfizer-BioNTech or Moderna Covid-19 vaccine could help increase protection levels for these higher-risk individuals.”

Background: The move comes as the Biden administration and public health experts worry about a potential new surge in cases. Across Europe, the highly infectious BA.2 variant is spreading rapidly and many fear it will soon cause cases to skyrocket in the U.S. BA.2, a subvariant of Omicron, accounts for more than 54 percent of cases nationally, up from 39 percent the previous week, the Centers for Disease Control and Prevention announced Tuesday.

The decision to authorize these booster shots is based on data from Israel, where approximately 700,000 adults received a Pfizer-BioNTech second booster, and a smaller study conducted on 120 U.S. adults who received an additional Moderna booster vaccine after receiving a Pfizer-BioNTech primary vaccine and booster. FDA also examined data on the immune response generated from individuals who received boosters in Israel as a part of an ongoing study. There have been no adverse events detected in these studies.

The U.S. has enough booster doses for these populations, Dawn O'Connell, the Department of Health and Human Services' assistant secretary for preparedness and response, said during a press conference on Monday. "What worries us is ... if a different variant comes up and we need a variant-specific boost in a few months. That would be quite a bit more expensive and we don't have those doses on hand, nor do we currently have the funding to cover those doses," she added.

What's next: The CDC will evaluate whether to recommend these boosters.

FDA's external advisory committee on vaccines is scheduled to meet on April 6 to discuss Covid-19 booster doses, as well as best practices for companies trying to develop shots against future strains of the virus.

Sarah Owermohle contributed to this report.