Pfizer Inc.’s vaccine provides less immunity to the omicron variant than to other major versions of Covid-19, according to laboratory experiments that still indicated a third dose may help stop the highly mutated strain.
Researchers at the Africa Health Research Institute in Durban, South Africa, found omicron resulted in about a 40-fold reduction in levels of neutralizing antibodies produced by people who had received two doses of the Pfizer-BioNTech SE shot, compared with the strain detected in China almost two years ago.
