A third dose increased antibodies 25-fold compared with two doses in the Omicron variant, the companies said. Still, two-doses may prove effective in preventing severe illness from Covid-19, they said.

Pfizer and BioNTech are working on an Omicron-specific vaccine that they hope to have available by March.

The companies’ early findings come a day after scientists in South Africa reported findings from early lab tests indicating the Pfizer-BioNTech vaccine generated one-fortieth of the infection-fighting antibodies against Omicron than against the original version of the virus.

Omicron was first identified by scientists in South Africa last month. Since then the World Health Organization has deemed it a “variant of concern.” And it has since been detected around the world, including in the U.S.

Researchers have been trying to understand how contagious the new strain is, as well as how well it might be able to evade Covid-19 vaccines and whether it causes severe disease. Some preliminary reports suggest the variant is more contagious, but may cause milder disease, though researchers say it is too early to know.

This story has been published from a wire agency feed without modifications to the text