Novavax's Phase 3 vaccine trial yields promising results

Biotech company Novavax has announced that NVX-CoV2373, its recombinant nanoparticle protein-based COVID-19 vaccine, has demonstrated 100% protection against moderate and severe disease, with 90.4% efficacy overall, and met the primary endpoint in its PREVENT-19 pivotal Phase 3 trial.

The study enrolled 29,960 participants across 119 sites in the US and Mexico to evaluate efficacy, safety and immunogenicity, with an emphasis on recruiting a representative population of communities and demographic groups most impacted by the disease.

In the placebo-controlled, observer-blinded study randomised 2:1, NVX-CoV2373 demonstrated overall efficacy of 90.4%, achieving its primary endpoint. 77 cases were observed — 63 in the placebo group and 14 in the vaccine group — with sequencing data available for 54 of these cases. All cases observed in the vaccine group were mild as defined by the trial protocol. 10 moderate cases and four severe cases were observed, all in the placebo group, yielding a vaccine efficacy of 100% against moderate or severe disease. NVX-CoV2373 also showed success among high-risk populations (defined as over age 65, under age 65 with certain comorbidities or having life circumstances with frequent COVID-19 exposure): vaccine efficacy was 91%, with 62 COVID-19 cases in the placebo group and 13 COVID-19 cases in the vaccine group.

Efficacy endpoints were accrued from 25 January through 30 April 2021 — a time when the Alpha variant, first identified in the UK, became the predominant strain in the US. Other strains, including variants of interest (VoI) and variants of concern (VoC), were also on the rise during the endpoint accrual window. PREVENT-19 met its key secondary endpoint, demonstrating 100% efficacy against variants not considered VoC/VoI. Of the sequenced cases, 35 (65%) were VoC, 9 (17%) were VoI and 10 (19%) were other variants. Against VoC/VoI, which represented 82% of the cases, vaccine efficacy was 93.2%, achieving a key exploratory endpoint of the study. 38 of the VoC/VoI cases were in the placebo group and six were in the vaccine group.

Preliminary safety data showed the vaccine to be generally well tolerated. Serious and severe adverse events were low in number and balanced between vaccine and placebo groups, with no single adverse event term reported by more than 1% of participants. In assessing reactogenicity seven days after Dose 1 and Dose 2, injection site pain and tenderness were the most common local symptoms, lasting less than three days. Fatigue, headache and muscle pain were the most common systemic symptoms, lasting less than two days.

“PREVENT-19 confirms that NVX-CoV2373 offers a reassuring tolerability and safety profile,” said Dr Gregory M Glenn, Novavax’s President of Research and Development. “These 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. Our vaccine will be a critical part of the solution to COVID-19 and we are grateful to the study participants and trial staff who made this study possible, as well as our supporters, including the US Government.”

The company intends to file for regulatory authorisations in the third quarter, upon completion of the final phases of process qualification and assay validation needed to meet chemistry, manufacturing and controls (CMC) requirements. Upon regulatory approvals, Novavax said 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 of 2021.

“Novavax is one step closer to addressing the critical and persistent global public health need for additional COVID-19 vaccines,” said Novavax President and CEO Stanley C Erck. “These clinical results reinforce that NVX-CoV2373 is extremely effective and offers complete protection against both moderate and severe COVID-19 infection.”

Image caption: A PREVENT-19 Phase 3 trial volunteer receives the vaccine at Research Your Health in Plano, Texas. Image credit: Matt Feldman, Novavax.

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