FDA advisers vote to simplify COVID vaccines, retire original "monovalent" shots

A panel of the Food and Drug Administration's outside vaccine advisers voted unanimously Thursday in favor of "harmonizing" the initial shots given to unvaccinated Americans with the updated booster shots rolled out last year, in a bid to simplify COVID-19 vaccines.

Once adopted by the FDA and Centers for Disease Control and Prevention, the change would effectively end use of the original "monovalent" shots that were developed initially in the pandemic, aimed at the original strain of the virus. Booster shots over the winter were "bivalent," containing components targeting the BA.4 and BA.5 variants.

That means unvaccinated people could effectively skip straight to the bivalent shots that had been given as booster doses over the winter.

"There's some unanswered questions and some things to work out, but I think this is absolutely the right thing to do for the program. It will make things simpler. And I know how we ended up this way, but I think this is a good decision to make and I'm supportive of it," said the CDC's Dr. Melinda Wharton, a member of the panel.

The vote comes amid a daylong meeting wrestling over the future of how and whether to update COVID-19 vaccines for future seasons. 

They were also asked whether they should convene annually by early June to decide on changes to the variants targeted by COVID-19 vaccines, ahead of a fall booster rollout, and to weigh in on ways to streamline the current myriad of immunization schedules.

"This is a consequential meeting to determine if we've reached a point in the pandemic that allows for simplifying the use of current COVID-19 vaccines, and if it is the moment to implement a more routine approach to periodically updating the strain composition," Dr. David Kaslow, director of the FDA's Office of Vaccines Research and Review, told the panel.

In the new framework suggested by the FDA, some Americans – including unvaccinated young children and older at-risk adults – would still be eligible for two doses, similar to what is recommended for influenza vaccines. 

Officials stressed that it was a "starting point" and that more data would likely be needed to finalize the proposal. However, manufacturers need guidance soon on how they can prepare for future updates, officials told the panel, in order to produce the next round of the shots.

The path suggested by the regulator already roughly mirrors the process used to update the COVID-19 vaccines last year, which are designed to include a component targeting the original strain of the virus and the BA.4 and BA.5 variants that were dominant over the summer.

The dominant variant today in the United States is the XBB.1.5 strain, a descendant of a different Omicron lineage which has grown in proportion mostly in the Northeast so far. 

Data published Wednesday by the CDC suggests the vaccines are working as well to protect against XBB.1.5 infections as they were previously against BA.5.

"What we observed is that if a variant has some sort of advantage, that it's generally taken over and swept across the country no matter where it's first detected. And I think there's reasonable suspicion that that will probably occur with XBB.1.5 as well," the CDC's Heather Scobie told the panel.

Executives from Pfizer told the committee that they would be able to manufacture new mRNA shots with BioNTech on the timeline laid out by the FDA.

However, that may be too short for traditional vaccines like Novavax to be revised. Strains for the annual flu vaccine are picked out months earlier, in February.

CBS News reporter covering public health and the pandemic.