vaccine dose

A booster dose of the Pfizer-BioNTech Covid-19 vaccine appears to provide strong protection against the omicron variant, the companies announced Wednesday.

They said a third dose of their vaccine provides a similar level of neutralizing antibodies to omicron, comparable to two doses against the original coronavirus and other variants that have emerged.

Blood samples from those who received only the primary series of the vaccine, on average, did see a 25-fold drop in antibodies against the new variant, indicating that two doses of the vaccine may not be sufficient to protect against infection with omicron.

As the highly mutated omicron variant, first identified in South Africa, spreads around the globe, scientists are racing to determine what whether the available vaccines will work against it.

The companies said the results are preliminary. The findings were detailed in a press release, and the full data have not yet been made available for other scientists to scrutinize.

But lab studies are only one piece of the puzzle. Other data are also needed to determine whether a new vaccine is needed. Scientists need to understand transmissible the omicron variant is (early indications suggest it's more contagious than the delta variant) as well as how sick it makes people (early data suggests the illness caused by the variant is milder).

The results from Pfizer-BioNTech are the first announced by vaccine makers. Tuesday, a South Africa research institute also released lab results on how the Pfizer vaccine fared against omicron, showing about a fortyfold reduction in vaccine-induced antibodies that could neutralize the new variant. That study didn't look at booster shots, however.

Pfizer-BioNTech has previously said it could develop a variant-specific vaccine within six weeks and ship initial batches within 100 days.

Moderna and Johnson & Johnson are expected to release lab results from the omicron variant in the coming days. Academic research institutions are also looking into how well the vaccine works against omicron.