Sat. Jan 29th, 2022

Vaccine makers are racing to update their Covid-19 shots against the newest coronavirus threat even before it’s clear a change is needed, just in case.

(photo courtesy: http://www.ft.com)

But authorities haven’t laid out what would trigger such a drastic step: If vaccine immunity against serious illness drops, or if a new mutant merely spreads faster?

“This is not trivial,” BioNTech CEO Ugur Sahin, Pfizer’s vaccine partner, said shortly before omicron’s discovery. A company could apply to market a new formula “but what happens if another company makes another proposal with another variant? We don’t have an agreed strategy.”

Omicron “is pulling the fire alarm. Whether it turns out to be a false alarm, it would be really good to know if we can actually do this – get a new vaccine rolled out and be ready,” said immunologist E. John Wherry of the University of Pennsylvania.

It’s too soon to know how vaccines will hold up against omicron. The first hints this week were mixed: Preliminary lab tests suggest two Pfizer doses may not prevent an omicron infection but they could protect against severe illness. And a booster shot may rev up immunity enough to do both.

Pfizer’s preliminary lab testing, released Wednesday, hint that might be the case but antibodies aren’t the only layer of defense. Vaccines also spur T cells that can prevent serious illness if someone does get infected, and Pfizer’s first tests showed, as expected, those don’t seem to be affected by omicron.

Also, memory cells that can create new and somewhat different antibodies form with each dose.

Pfizer expects to have an omicron-specific candidate ready for the Food and Drug Administration to consider in March, with some initial batches ready to ship around the same time, chief scientific officer Dr. Mikael Dolsten.

“You’re really training your immune system not just to deal better with existing variants, but it actually prepares a broader repertoire to deal with new variants,” Dolsten said.

How aggressive a mutant is also plays a role in whether to reformulate the vaccine. Omicron appears to spread easily but early reports from South African scientists hint that it might cause milder infections than previous variants.

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