Novavax says its Covid-19 vaccine is 89 percent effective, but less so against South African variant

Novavax, which is based in Maryland, has never brought a vaccine to market. The Trump administration awarded the company $1.6 billion to develop and test the vaccine, begin large-scale manufacturing and reserve 100 million doses.

Trial details: Novavax tested its vaccine in the U.K. during a period when a different variant of the virus — first detected in Britain and more transmissible than earlier versions — began circulating. The company’s analysis of the 15,000-person Phase III trial found that the vaccine was 95.6 percent effective against the original Covid-19 strain and 85.6 percent effective against the U.K. variant, B.1.1.7.

Early data from a separate 4,400-person Phase IIb clinical trial in South Africa found that the vaccine was just 49.4 percent effective against the variant first discovered in that country. More than 92 percent of sequenced PCR samples taken from Covid patients in the South African trial were identified as that variant, which is known as B.1.351.

Novavax says it is developing booster shots of its vaccine to better protect against new strains of Covid and plans to start testing them in people in the second quarter of 2021.