Pfizer says COVID-19 shot is 91 per cent effective in updated data, protective against South African variant

Pfizer and BioNTech say their COVID-19 vaccine is about 91 per cent effective at preventing the disease, citing updated trial data that included participants inoculated for up to six months.

The shot was also 100 per cent effective in preventing illness among trial participants in South Africa, where a new variant called B1351 is dominant.

However, that rate was derived from a relatively small number of nine infections observed there, which were all in the placebo group.

While the new…