(Bloomberg) -- Bivalent Covid-19 shots should become the standard form of the vaccine, US advisers said, part of a plan to offer a single booster to the public each year that gives protection against the most recent, dominant strains.

Anyone getting a Covid shot for the first time now receives a vaccine designed in 2020, when the virus looked a lot different than it does today. A panel of 21 advisers to the Food and Drug Administration voted unanimously Thursday to make bivalent vaccines, designed to fight the BA.4 and BA.5 omicron strains, the primary option. 

Bivalent shots made by Pfizer Inc. and Moderna Inc. have been shown to fight circulating strains effectively. The FDA doesn’t have to follow the recommendations of the Vaccines and Related Biological Products Advisory Committee, but it usually does.

This vote paves the way for a plan under which health officials would meet each year to review strains of the virus for inclusion in the shots, just as they do with flu, for use in September. There are more than a dozen different Covid vaccine regimens and immunization schedules in use in the US, which leads to complexities in implementation and communication, said David Kaslow, director of the FDA’s office for vaccines research and review.

“We’re now in a reasonable place to reflect on the development of the Covid vaccines to date to see if we can simplify the approach to vaccination in order to facilitate the process of optimally vaccinating and protecting the entire population moving forward,” Peter Marks, director of the FDA’s Center for Biologics Evaluation and Research, said at the panel meeting.

Consistent Regimen

Healthy adults would receive one Covid shot each fall in the FDA plan, while children, the elderly and those with compromised immunity would receive two doses. Ad-hoc boosters could be used if a particularly vaccine-evasive strain of Covid arises.

Using the same Covid vaccine strain composition for both primary series and boosters would simplify immunization schedules, Kaslow said. Covid shot-makers are developing products that would simplify the process further by combining their Covid vaccines with annual immunizations against flu. 

The FDA has begun a study of co-administration of flu and Covid vaccines that should be complete before the 2023-2024 influenza season begins, health officials said. For the time being, there’s concern about administering Covid and flu shots together.  

Safety Issues

One database of adverse vaccine events detected a higher risk of stroke among older adults who had received Pfizer’s updated booster. The signals were not picked up in other large databases, FDA officials said then, but the agency will continue investigating the issue.  

“Is there any reason to believe that spreading those out temporarily might reduce the stroke risk?” said Jeannette Yen Lee, a biostatistician at the University of Arkansas for Medical Sciences who’s a temporary voting member of the panel.  

“I don’t think that the evidence are sufficient to conclude that there’s an association there,” responded Tom Shimabukuro, deputy director of the Centers for Disease Control and Prevention’s Immunization Safety Office. “Talking about spacing out the vaccines may be a bit premature at this time.”

--With assistance from Madison Muller.

(Updates with panel members’ comments in second and third sections.)

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