Pfizer-BioNTech Covid-19 shot loses power against Omicron variant, but booster restores protection

People who have received two doses of the Pfizer-BioNTech Covid-19 vaccine are likely susceptible to infection from the Omicron variant of the coronavirus, but a third shot restores antibody activity against the virus, the companies said Wednesday.

Their findings are based on lab experiments using the blood of people who have received the vaccine. In a press release, the companies reported a 25-fold reduction on average in the levels of neutralizing antibody activity against the Omicron variant in people who had received two doses of their Covid-19 vaccine. But they also...