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If the Food and Drug Administration decides to update Covid-19 vaccines to take better aim at Omicron or other variants, it is unlikely to go it alone.

Instead, a senior FDA official told STAT, the agency expects to take part in an internationally coordinated program aimed at deciding if, when, and how to update Covid-19 vaccines. The approach would ensure decisions are not left solely to individual vaccine manufacturers.


“We can’t have our manufacturers going willy-nilly [saying], ‘Oh well, the EMA decided they wanted this composition, but FDA wanted that composition,’” the official said, referring to the European Medicines Agency. “So we are very much of the mind that we would like to be part of a more global process in helping to come to what vaccine composition there should be now.”

The approach will likely be modeled on — though perhaps not identical to — a program used for decades to decide which strains should be included in influenza vaccines, the official said, speaking on condition of anonymity.

The World Health Organization has been working to organize such a process for Covid-19 vaccines for some time. Last week, regulatory agencies from around the globe met to discuss, among other things, what would be required to update the vaccines.


“I think we very much are going to try to align with our large regulatory colleagues like the EMA,’’ the official said. “I think we’d like to try to work with WHO so that we are in line and we will probably work through a process that looks similar to what we do for flu, if not identical.”

Last month, the head of the WHO’s health emergencies program stressed the importance of coordinating vaccine updates, with input from scientists, public health agencies, regulatory bodies, and industry.

“We believe that these are going to be big decisions and they’re going to have real consequences. They need to be done quickly but they also need to be done carefully,” Mike Ryan told STAT. “We just need to be really focused at this point on pulling the best data together that we can, the best evidence and make good decisions together. If it’s purely left to be a commercial decision, I’m not so sure that decision will necessarily be the best one.”

The Omicron variant’s capacity to partially evade the immune protections elicited by Covid vaccines is making the planning for a process to update vaccines more critical. Several of the manufacturers are testing Omicron-based vaccines and the partnership of Pfizer and BioNTech has already indicated it expects to have data by early March. The company has suggested it may apply for authorization for an Omicron-specific booster, or a bivalent vaccine, which would contain the Omicron strain and another version of the SARS-CoV-2 virus.

But it’s unclear at this point whether swapping out the original strain of the virus and replacing it one that targets the Omicron variant would be the right approach to take. This extraordinary wave of the pandemic could end in record time; Omicron could remain the dominant strain or could be replaced in the near term by something else. If future variants are markedly different, the cross-protection generated by an Omicron-based vaccine might not be as robust as the protection generated by the original vaccines or those targeted at, for example, the Delta variant.

The studies that are underway will show if and how well blood samples from people vaccinated with an Omicron-based vaccine are able to neutralize earlier versions of the virus.

“Until we have that, we really won’t know the answer to this question. And so we do have to be cautious and we have to be agile,” the FDA official said. “We probably don’t want to take the chance that we’re going to abandon something that seems to be at least working reasonably well for something else unless we have good evidence that what we’re going to is going to be better.”

The official said that in addition to the need to harmonize vaccine updates internationally, there’s a domestic imperative at play. The U.S. has adopted a mix-and-match strategy, one that allows people to be boosted with a vaccine brand that differs from the one they received as their primary vaccine series.

“We do not particularly relish the idea of each manufacturer having their own flavor of secret sauce,” the official said. “If you start to have specific manufacturer booster compositions, that could actually create some challenges here.”

The flexibility of the mix-and-match approach will be crucial if people require annual Covid booster shots. Most flu shots are interchangeable — with the exception of a few that are targeted to older adults or children. The goal with Covid vaccines is to have them work in the same manner, if it becomes clear regular or annual boosting will be needed, the FDA has said.

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