Novavax's COVID-19 vaccine shows 90.4% efficacy in pivotal study

Novavax announced Monday that its candidate COVID-19 vaccine NVX-CoV2373 demonstrated 100% protection against moderate and severe disease and 90.4% efficacy overall in the Phase III PREVENT-19 study. The company reiterated a recent delayed timeline to seek marketing authorisations for the recombinant nanoparticle protein-based vaccine in the third quarter.

The trial enrolled 29,960 adults in the US and Mexico and investigated two injections of  NVX-CoV2373, formulated with Novavax's Matrix-M adjuvant, or placebo given 21 days apart. The study's primary endpoint was PCR-positive symptomatic mild, moderate or severe COVID-19 illness diagnosed at least seven days after the second dose.

Effective against variants of concern

Results showed that the trial achieved its primary endpoint, with only 14 cases of COVID-19 seen in those who received NVX-CoV2373, versus 63 in the placebo group. Novavax noted that all cases of coronavirus infection in the vaccine group were mild, compared to 49 in the placebo group, which also included 10 cases of moderate disease and four severe cases.

The company added that NVX-CoV2373 demonstrated efficacy of 93.2% against variants of concern/interest, which accounted for 82% of the 54 COVID-19 cases that had sequence data available. Novavax explained that during the period from January through April when the efficacy endpoints were accrued, the Alpha (B.1.1.7) variant became the predominant strain in the US. The drugmaker noted that 38 of the variants of concern/interest cases were in the placebo group and six were in the vaccine group. Meanwhile, NVX-CoV2373 showed 100% efficacy against variants not considered to be of concern/interest.

Further results showed that NVX-CoV2373 was also effective in high-risk populations, with efficacy of 91%, whilst all hospitalisations occurred in the placebo arm. With regards to safety, Novavax said that serious and severe adverse events were "low in number and balanced between vaccine and placebo groups."

Backs up earlier Phase III data from UK

In March, Novavax announced that NVX–CoV2373 showed 89.7% efficacy overall at the final analysis of a Phase III UK-based trial, with efficacy of 86.3% against the Alpha variant. "PREVENT-19 confirms that NVX-CoV2373 offers a reassuring tolerability and safety profile," remarked R&D president Gregory Glenn, adding that the "data show consistent, high levels of efficacy and reaffirm the ability of the vaccine to prevent COVID-19 amid ongoing genetic evolution of the virus."

Novavax suggested Monday that if NVX-CoV2373 is approved, it remains on track to reach manufacturing capacity of 100 million doses per month by the end of the third quarter and 150 million doses per month by the end of the fourth quarter. "Many of our first doses will go to…low- and middle-income countries, and that was the goal to begin with," CEO Stanley Erck said.

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