A top Pfizer executive says the company is hopeful that booster shots will provide sufficient protection against the Omicron variant — but has already envisioned a timeline for the development of a new vaccine if that’s not the case.
Mikael Dolsten, Pfizer’s chief scientific officer, likened the company’s researchers to firefighters: They don’t know how serious the blaze will be, but need to prepare for the worst. And in this case, the worst would mean the need to develop new vaccines.
“We do take the new variant of concern, Omicron, with seriousness,” Dolsten told STAT. “It can indeed be a potential new threatening wave … although we don’t know that yet. But we always start with being prepared for the worst.”
Like their rival Moderna, Pfizer and its partner BioNTech say a variant-focused vaccine could be ready in less than 100 days. Dolsten said Pfizer and BioNTech have already started to make a DNA template of a new vaccine construct, the next step in the development of a new vaccine after making the mRNA and the lipid envelope it will go into.
It’s not clear whether a new clinical trial would be needed for regulatory approval, based on Pfizer’s previous conversations with the FDA, Dolsten said. It’s possible that a booster focused on the Omicron strain could be authorized, based on studies that have already been done with vaccines based around the Beta and Delta variants.
If one is required, though, Pfizer would have enough experimental vaccine to begin a clinical trial within about two months, Dolsten said. Such a study would be small, and would look at the safety of the vaccine and the immune response to it. It is possible to see how much a vaccine increases antibody levels within seven days after the second dose, so he believes a study could be completed within a month.
In about three months — by early March — Dolsten said Pfizer and BioNTech would be able to produce doses at “very high commercial scale.” That would mean being able to produce a billion doses of vaccine a quarter, or about 330 million doses a month. Dolsten imagines that if a new Omicron-specific vaccine is needed, it would replace the current vaccine, because so far new strains of the SARS-CoV-2 virus that have become problematic have out-competed existing strains. At the same time, Dolsten said, it would be possible to have two different versions of the vaccine: one for the older strains and one for Omicron.
He emphasized, however, that a great many questions about Omicron still loom.
“We don’t know whether it will really outcompete Delta in a more diverse population, and we don’t know yet whether our vaccine does cover it sufficiently,” Dolsten said. He said that he is “cautiously optimistic” that, especially for those who have received a third dose of the vaccine, also known as a booster, the existing vaccine will prove protective against Omicron.
Dolsten’s argument is that booster shots lead to greater levels of antibodies that neutralize the virus, and also more diverse types of antibodies that give broader protection against new variants. While some experts have been skeptical of the push to give boosters in developed countries like the U.S., Dolsten insisted that the boosters are important.
“There is no vaccine constraint in volume,” he said. “We should boost and we should vaccinate as many unvaccinated that are willing to get vaccinated.”
Dolsten said that it will become clear whether a new Omicron variant-focused vaccine is needed later this month, as Pfizer and BioNTech test whether the neutralizing antibodies made by the existing vaccine have an impact on boosters and look at data for how Omicron is spreading in the real world. That will tell researchers, for instance, whether cases are occurring in those who are unvaccinated, those whose vaccine protection is waning, or, in a worst-case scenario, in people who were recently vaccinated.
Dolsten said he hoped Pfizer’s new anti-Covid pill, which must be combined with another drug, ritonavir, could be used to help slow outbreaks, because treating people should make them less likely to transmit. The Food and Drug Administration is reviewing the pill for an emergency use authorization. Dolsten said that Pfizer could make 200,000 doses available this year, and will be able to make 80 million treatment courses next year, including 20 million in the first half of next year.
Whether or not a new vaccine is needed now, Dolsten said, it appears that new variants of concern are cropping up every few months. He suggested that it may only be a matter of time before a new shot is needed.
Source: STAT News