What happened

Shares of Novavax (NVAX -3.35%) were up 8.1% as of 10:22 a.m. EST on Friday after rising as much as 15.8% earlier in the session. The big gain came after the company announced impressive results from the final analysis of a late-stage study evaluating COVID-19 vaccine candidate NVX-CoV2373.

So what

Investors clearly think that Novavax's final analysis increases the likelihood that NVX-CoV2373 will win Emergency Use Authorization (EUA) in the U.K. and the U.S. They're probably right.

Scientist holding a syringe and a vaccine vial

Image source: Getty Images.

Novavax reported that NVX-CoV2373 provided 100% protection against severe cases of COVID-19. The biotech confirmed an efficacy of 96.4% against the original strain of the SARS-CoV-2, the coronavirus that causes COVID-19. This level is higher than the efficacy levels originally reported for all three of the other COVID-19 vaccines that have won EUA so far in the U.S.

The company also said that it confirmed efficacy for NVX-CoV2373 against newer coronavirus variants discovered in the U.K. and South Africa. As expected, however, the vaccine didn't provide as much protection against these variants. The late-stage study found 86.3% efficacy against the U.K. variant.

Novavax also conducted a phase 2b study in South Africa. NVX-CoV2373 demonstrated an overall efficacy of 48.6% in this clinical trial, with most of the cases of COVID-19 due to the B.1.351 variant first identified in South Africa. The vaccine's efficacy among HIV-negative participants was 55.4%.

Now what

There are two potential catalysts for the biotech stock in the near term. Novavax expects to file for EUA in the U.K. early in the second quarter of 2021. The company hopes to also submit for EUA in the U.S. soon afterward. Just how quickly that filing will come, though, will depend on whether the U.S. Food and Drug Administration allows Novavax to base its submission on its U.K. study results.