U.S. pharmaceutical company Novavax announced Thursday that its coronavirus vaccine, one of the six funded by the federal government’s Operation Warp Speed, was 90 percent effective against the infectious disease, according to an international analysis. The company conducted efficacy research in Britain, South Africa, the United States, and Mexico and found that its vaccine offered strong protection against the virus everywhere except South Africa. There, Novavax found, the jab was just 50 percent effective at preventing infection. “The amount of change has been a bit of a surprise to everyone,” Novavax CEO Stanley Erck told The New York Times. Moderna and Pfizer have also said that their vaccines are less effective against the South African variant, despite being more than 90 percent effective against other strains of the virus.