A small company that's been developing new vaccines since Reagan was President, Novavax (NVAX -0.81%) announced its first late-stage clinical trial victory on Thursday afternoon. The company's COVID-19 vaccine candidate, NVX-CoV2373, reduced volunteers' chances of getting COVID-19 by 89.3% compared to a placebo. 

A smiling medical professional with a face mask pulled down beneath their chin.

Image source: Getty Images.

Novavax's first phase 3 clinical trial win comes from a 15,000-patient study in the U.K. A majority of the positive cases reported were of the now-predominant U.K. variant. NVX-CoV2373 appears just as effective at preventing the U.K. variant as the original coronavirus strain.

Investigators ran an interim analysis after 62 participants tested positive for COVID-19. All but six of them were in the placebo group. With a 95% confidence interval adjustment, that works out to an 89.3% efficacy rate overall.

Of the aforementioned 62 cases, 32 had the U.K. strain, 24 had the original strain, and six were unknown. Extrapolating from this limited sample, it looks like NVX-CoV2373 is 85.6% effective against the U.K. variant and 95.6% effective against the original recipe. 

Unfortunately for those of us in the U.S., the Food and Drug Administration isn't willing to review an emergency use authorization application without results from a mostly domestic phase 3 study. The company has randomized over 16,000 patients in a North American trial designed to meet the FDA's requirements. It has a total enrollment goal of 30,000 patients.