Novavax data shows its vaccine is successful against traditional COVID-19 strains.

Novavax, a small Maryland company that has floundered in product development over its 30 years of existence, revealed data from the U.K. trial of its COVID-19 vaccine today. The vaccine was 89% effective in preventing clinical disease from COVID-19, nearly as effective as the leading RNA vaccines from BioNTech-Pfizer and Moderna. This provides another option for COVID-19 immunization.

Novavax has been almost completely supported in vaccine development by the U.S. federal government. The vaccine uses more traditional technology than the RNA vaccines that involves a copy of the COVID spike protein made in insect cells. This protein is then mixed with an inflammatory compound called an adjuvant to induce an immune response when injected. 

When Novavax announced on Thursday that its Covid-19 vaccine offered robust protection against the prototypic SARS-CoV-2 virus, it also reported that the vaccine is not nearly as effective against the fast-spreading South African variant. This was in contrast to Pfizer and Moderna’s data earlier this week that showed reduced immunity but efficacy against this variant.

That could be a problem for Novavax since this variant has now been identified in the United States in two unrelated people in South Carolina. Compared to the RNA vaccines, it is also more difficult to change this vaccine to cover variants.

Novavax is one of the six vaccines supported by Operation Warp Speed nine months ago (or what was formally known as Warp Speed, since the name has been dropped). The company has run trials in Britain, South Africa, the United States, and Mexico. Its trials in the U.S. have fallen behind, and the company blamed this on the availability of the RNA vaccines.

It said Thursday that an early analysis of its 15,000-person trial in Britain revealed that the two-dose vaccine had an efficacy rate of nearly 90 percent there. But in a small trial in South Africa, the efficacy rate dropped to just under 50 percent.

Almost all the COVID-19 cases in South Africa were caused by the virus variant there, known as B.1.351. The results also indicated that many trial participants were infected with the variant even after they had been infected with standard Covid-19. This might be a reason to get a COVID-19 vaccine even if you have had COVID-19.

A disclosure: I was a member of the scientific advisory board of Novavax for its first ten years, but no longer have any ties to the company or apparent financial interest.