FDA approves 2nd omicron booster for high-risk people

• Most people who have received a single shot of the bivalent vaccine aren't eligible for a second dose, but the FDA could revise criteria after an expert panel meets to discuss the topic in June.

Details: Tuesday's decision means those over 65 can get a second booster no sooner than four months after the first.

• Immunocompromised people may receive the second shot at least two months after receiving the first dose "and additional doses may be administered at the discretion of, and at intervals determined by, their health care provider," the FDA said.
• The agency made additional changes, saying that unvaccinated people may receive a single dose of the bivalent vaccine as their first shot, rather than multiple doses of the original monovalent vaccine.
• Children between six months and five years old who have received up to three doses of the monovalent vaccine may receive a bivalent vaccine shot, but the number of doses they receive "will depend on the vaccine and their vaccination history," per the FDA.
• The monovalent shots from Moderna and Pfizer are no longer authorized for use in the U.S.

What they're saying: "At this stage of the pandemic, data support simplifying the use of the authorized mRNA bivalent COVID-19 vaccines and the agency believes that this approach will help encourage future vaccination," said Peter Marks, director of FDA's Center for Biologics and Research.

• "Evidence is now available that most of the U.S. population 5 years of age and older has antibodies to SARS-CoV-2 ... either from vaccination or infection that can serve as a foundation for the protection provided by the bivalent vaccines," Marks added.

Catch up fast: An FDA advisory committee in January unanimously recommended that the U.S. replace initial doses of the original COVID monovalent shots with bivalent ones to target omicron subvariants, directing Pfizer, Moderna and Novavax to focus on bivalent vaccines.

• At the time, the FDA requested that the panel consider a future immunization schedule and proposed a yearly one-dose schedule for the general population and two doses for high-risk individuals.
• The panel, however, did not make any specific recommendations on that because members said they needed additional data on different population groups to determine what dosage was appropriate for each group.

What we're watching: A panel for the Centers for Disease Control and Prevention is scheduled to meet on Wednesday to discuss the second booster strategy.

• If panel recommends the shot for high-risk individuals and CDC Director Rochelle Walensky signs off, the boosters could be available this week.

Zoom out: The FDA's decision comes as a new subvariant, XBB. 1.16, known as Arcturus, has been spreading around the world and gaining traction in the U.S.

Don't forget: The COVID public health emergency is set to end in less than a month, shifting the cost of vaccines and other countermeasures to the private market.