Pfizer, BioNTech say booster dose needed to fight Omicron

PFIZER and BioNTech said initial lab studies show a third dose of their Covid-19 vaccine may be needed to neutralise the Omicron variant, results that will accelerate booster-shot drives around the world.

Company researchers observed a 25-fold reduction in neutralising antibody levels versus the variant, compared with the original strain of the virus, in people who got just 2 shots.

However, boosting with an additional shot of the vaccine raised antibodies 25-fold against Omicron, giving a similar level of the protective proteins as observed against those earlier versions after the standard 2 doses, the vaccine partners said in a statement.

The lab findings indicate that 2 doses of the vaccine "may not be sufficient" to protect against infection with the Omicron strain, the companies said in a release.

Along with stimulating the booster push, that may increase the likelihood that an Omicron-targeted shot may ultimately be required. Pfizer said this would be ready by March.

Uncertainty over vaccine efficacy against the new variant has fuelled market volatility and prompted travel restrictions since Omicron was identified in southern Africa last month.

The Pfizer-BioNTech results add to data from around the world attempting to assess the impact of Omicron on vaccine protection.

South African researchers found a 41-fold drop in levels of virus-blocking antibodies against Omicron, compared with the strain circulating at the start of the pandemic.

A German team found a 37-fold drop in antibodies against Omicron versus the highly transmissible Delta variant.

However, a study from Stockholm's Karolinska Institute was more optimistic, finding the decline in antibodies against Omicron was only slightly worse than for Delta.

T cells, another virus-fighting component of the immune system, should still be able to respond to Omicron.

About 80 per cent of viral features called epitopes that are recognised by T cells are unchanged in the variant, Pfizer and BioNTech said.

The companies said that they will be watching closely to see how quickly immunity against Omicron wanes over time even after a third dose.

"It's clear from these preliminary data that protection is improved with a third dose," Pfizer chief executive officer Albert Bourla said in the statement.

Boosters could help people everywhere "get through the winter season" as the companies work on adapting the vaccine, BioNTech chief executive Ugur Sahin said.

An adapted vaccine should provide "a prolonged protection compared to the current vaccine," he said. BLOOMBERG