Pfizer Inc and BioNTech said on Thursday their Covid-19 vaccine is around 91% effective at preventing the disease, citing updated trial data that included participants inoculated for up to six months.
The shot was also 100% effective in preventing illness among trial participants in South Africa, where the new variant, B1351, is dominant. However, the rate was derived from a relatively small number of nine infections, which were all in the placebo group, Pfizer said.
