Novavax Covid Shot 93% Effective Against Variants in Trial

Novavax Inc.’s Covid-19 vaccine candidate showed strong efficacy against the coronavirus, including mutated variants, in a large trial.

The shot was 90% effective at preventing symptomatic Covid and 100% effective at preventing moderate and severe symptoms, the U.S. biotech firm said Monday. The shot was 93% effective against variants of concern, it said.

Novavax shares rose 8.5% in premarket U.S. trading.

The vaccine uses a recombinant protein technology, also used in the vaccine candidate developed by Sanofi and GlaxoSmithKline Plc. At over 90%, the overall efficacy of the vaccine is close to reported rates for mRNA shots developed by Pfizer Inc. with BioNTech SE and by Moderna Inc., as well as the Sputnik V vaccine from Russia, using viral vector technology. However, immunologists tend to caution against comparing efficacy results across different trials as conditions and evaluation methods aren’t the same.

Novavax’s phase 3 trial included almost 30,000 participants in the U.S. and Mexico and studied the vaccine’s efficacy against major variants circulating in the U.S., as defined by the Centers for Disease Control and Prevention. Only one case of the highly contagious delta strain, which was first identified in India and remains rare in the U.S., was detected among trial participants, so the vaccine’s efficacy against it isn’t conclusive.

In results from a 15,000-person trial in the U.K. released in March, the shot demonstrated 90% effectiveness at preventing Covid symptoms across variants and the original version of the virus.

The company previously said it wouldn’t file for vaccine authorization in the U.S. and Europe until the third quarter of the year. Novavax says it’s on track to reach manufacturing capacity of 100 million doses per month by the end of the third quarter and 150 million per month by the end of 2021.

“Novavax is one step closer to addressing the critical and persistent global public health need for additional Covid-19 vaccines,” Chief Executive Officer Stanley C. Erck said in a statement. “Novavax continues to work with a sense of urgency to complete our regulatory submissions and deliver this vaccine, built on a well understood and proven platform, to a world that is still in great need of vaccines.”