Pfizer’s omicron booster improves immune response, company says

Pfizer’s two omicron-focused booster vaccines massively improve a person’s immune response against the COVID variant, the company said Saturday.

Across clinical trials involving more than 1,200 people, Pfizer tried two different omicron boosters: one focused solely on the omicron variant (called a monovalent vaccine) and one that used Pfizer’s initial vaccine but tweaked it to also combat omicron (called bivalent).

The monovalent booster increased immune response between 13- and 19-fold, a massive increase that varied based on the dose size. The bivalent shot boosted immune response between 9- and 10-fold, Pfizer said.

All clinical participants had already received three shots of the initial vaccine.

“Based on these data, we believe we have two very strong omicron-adapted candidates that elicit a substantially higher immune response against omicron than we’ve seen to date,” Pfizer CEO Albert Bourla said in a press release.

The omicron boosters are still a long way from appearing in American pharmacies and doctor’s offices. The first step will come Tuesday when a group of scientific advisers with the Food and Drug Administration meet to work on vaccine policy in the U.S.

Earlier this month, Moderna released its results, also encouraging, from its own omicron-targeting booster.

The current COVID vaccines are still highly effective at preventing severe disease and death, but the omicron variant rendered them relatively punchless for preventing infection.