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 a new variant called B1351 is dominant, although the number of those participants was relatively small at 800.
While the new overall efficacy rate of 91.3% is lower than the 95% originally reported in November for its 44,000-person trial, a number of variants have become more prevalent around the world since then.