Novavax Posts Positive First Look at Phase III COVID-19 Vaccine Results

Novavax_Jakub Porzycki/NurPhoto via Getty

Jakub Porzycki/NurPhoto via Getty Images

Shares of Novavax soared more than 44% in premarket trading after the company announced a first Phase III analysis of its COVID-19 vaccine candidate which shows the medication demonstrated 89.3% efficacy in a large-scale study conducted in the United Kingdom that included the most common strain of the virus, as well as variants.

Maryland-based Novavax said efficacy of its NVX-CoV2373 vaccine was 95.6% against the original strain and 85.6% against the U.K. variant that has swept across that nation. Novavax also reported progress from an ongoing Phase IIb study in South Africa that did include a newer and more virulent strain in that part of the world.  Overall for that study, the results showed a 60% efficacy. However, the Phase IIb study included patients who were HIV-positive. Among those immuno-compromised patients included in the study, the efficacy against the South African strain dropped to 49%.

Stanley C. Erck, president and chief executive officer of Novavax, said the data from the Phase III study in the U.K. shows that NVX-CoV2373 has the potential to play an important role in solving this global public health crisis.

“NVX-CoV2373 is the first vaccine to demonstrate not only high clinical efficacy against COVID-19 but also significant clinical efficacy against both the rapidly emerging U.K. and South Africa variants,” Erck said in a statement.

NVX‑CoV2373 consists of a stable, prefusion protein made using its proprietary nanoparticle technology and includes Novavax’s proprietary Matrix‑M adjuvant. Data from a Phase I/II study showed that NVX‑CoV2373 produced antibodies in healthy patients, a sign the vaccine is working as intended. The vaccine was also well-tolerated in those patients, the company said.

With a number of emerging COVID-19 strains across the globe, Novavax initiated development of new constructs against those new threats this month. The company said it soon expects to select ideal candidates for a booster and/or combination bivalent vaccine for the new strains. Novavax plans to initiate clinical testing of these new vaccines in the second quarter of this year.

“A primary benefit of our adjuvanted platform is that it uses a very small amount of antigen, enabling the rapid creation and large-scale production of combination vaccine candidates that could potentially address multiple circulating strains of COVID-19,” Gregory M. Glenn, president of Research and Development at Novavax said in a statement. “Combined with the safety profile that has been observed in our studies to-date with our COVID-19 vaccine, as well as prior studies in influenza, we are optimistic about our ability to rapidly adapt to evolving conditions.”

The Phase III U.K. study included more than 15,000 participants between 18-84 years of age. Approximately 27% of the trial participants were over the age of 65, the company said. The primary endpoint of the U.K. Phase III trial is based on the first occurrence of PCR-confirmed symptomatic (COVID-19 with onset at least seven days after the second dose of the vaccine in patients who had previously tested negative for the virus. The first interim analysis is based on 62 cases from the Phase III study. Of those, 56 cases of COVID-19 were observed in the placebo group compared to six cases in the NVX-CoV2373 group. That resulted in an estimated vaccine efficacy of 89.3%. Of the 62 cases, 61 were mild or moderate, and one was severe. That severe case was in the placebo group, Novavax said.

With the strong interim results, Novavax has begun a rolling submission for regulatory authorization in the United Kingdom. The company said it expects to share further details of the U.K. trial results as additional data become available.

Regarding the South African study, the company said 90% of the reported COVID cases in that study were associated with the more virulent strain. What may be concerning is one-third of the patients included in this study were previously infected with the SARS CoV-2 virus. Pre-trial infections are thought to have been caused by the original COVID-19 strain, while the subsequent infections during the study were largely the new variant. These data suggest that prior infection with COVID-19 may not completely protect against subsequent infection by the South Africa escape variant, however, vaccination with NVX-CoV2373 provided significant protection, the company said.

Studies in the United States and other countries are ongoing. It is unclear if the Phase III data from the U.K. study could be submitted to the U.S. Food and Drug Administration for potential Emergency Use Authorization. In the U.S., Novavax is conducting the PREVENT-19 trial to assess the vaccine. So far, the company has recruited more than 16,000 participants and hopes that number will climb to 30,000 by the middle of February. That study is being conducted with support from the federal government.

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