Omicron could require new vaccines if two factors were met, Pfizer's top scientist told Insider.
The variant would need to outcompete Delta globally and reduce protection from the current vaccines.
Pfizer's Mikael Dolsten shared the plan to have an Omicron-specific shot ready by March.
Mikael Dolsten, Pfizer's chief scientific officer, told Insider the drugmaker was already preparing for the worst-case scenario: A shot specific to the Omicron variant will be needed. But before he draws that conclusion, Dolsten is watching how two unknown elements play out in the next few weeks, he said.
The first unknown is how well the current vaccines hold up against Omicron. The answer won't be a binary yes or no but a sliding scale of protection.
Experts generally do not anticipate that Omicron will completely evade all protection from the current shots. Previous research suggested many more mutations were needed to reach that point.
But other variants of concern, including the Beta and Delta strains, have shown they can diminish vaccine protection. Omicron may be more concerning because it has far more mutations on the spike protein, which is the target of vaccines.
Most experts expect Omicron to decrease levels of neutralizing antibodies, virus-fighting proteins that play a key role in our immune response. The question that laboratory testing will help answer is just how much of a decline this variant can cause.
Dolsten said a tenfold decrease in antibodies would make him concerned that the current vaccines wouldn't be sufficient and an Omicron-specific shot would be needed.
"If we exceed a tenfold drop in neutralization of Omicron, I think we are starting to enter the yellow to red zone, when your immunity is likely lowered and there's limited time after your boost until waning," Dolsten said.
Laboratory tests, which will likely come out over the next week or two, could also show the vaccines holding up well enough against Omicron, Dolsten said. For the time being, the best protection is getting vaccinated or getting a booster of one of the current shots.
"We remain cautiously optimistic that our current vaccine with the boost can provide meaningful protection," he said.
It's too early to know whether Omicron will overtake Delta, Dolsten says
If there is a major drop in protection, a second question will become consequential: Will Omicron overtake Delta around the world? "We'll likely know in December," Dolsten said.
If Omicron does become the world's dominant variant, new vaccines will need to be distributed everywhere. But if it dissipates or fails to outcompete the Delta variant, new vaccines probably won't be widely needed.
There's a reason for measured optimism here. The Beta variant previously spooked scientists by showing the ability to significantly degrade the vaccine response. But despite that attribute, it never took off around the world.
"It's still too early to understand whether Omicron has the same transmissible ability as Delta to become a pandemic strain, or if it will be similar to the Beta strain that started in South Africa but really became a local epidemic and more or less vanished," Dolsten said.
Pfizer previously developed Beta- and Delta-specific shots but didn't need to use either of them. Beta fizzled out, and the current vaccines held up well enough against Delta.
Those two factors will determine whether Pfizer is running another fire drill with an Omicron-specific booster shot or this is the first time a new vaccine is necessary.
With antiviral pills bridging the gap, Dolsten says a new shot may be ready by March
If the worst-case scenario of Omicron defeating the current vaccines does come to fruition, Dolsten said, Pfizer will be ready. His goal is to be prepared to launch a new vaccination campaign by March, if needed.
Pfizer is far from alone, as many drug companies are prepping for Omicron. Several other vaccine developers, including Moderna, Novavax, and Johnson & Johnson, are working on boosters tailored to Omicron.
Pfizer's plan is to finalize its manufacturing process for the Omicron-specific shot by the end of February. Dolsten said he believed the company might not have to run clinical trials to win an OK and instead just share manufacturing details with regulators on the strain shift. He said they would share their previous experience in developing and testing Beta- and Delta-specific shots.
Dolsten said Pfizer could start commercial production in March, increasing its output each week up to 80 million doses a week. At the full run rate, Pfizer can pump out 1 billion doses each quarter, Dolsten said.
Before then, Dolsten said he thought the company's experimental antiviral pill, Paxlovid, would have a major effect. A clinical study in unvaccinated people at high risk of severe disease showed the treatment reduced hospitalizations and deaths by 89%.
US regulators are reviewing the drug, and within the next few months, Paxlovid could win authorization and start being used to treat COVID-19 patients.
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