Novavax Confirms High Levels of Efficacy Against Original and Variant COVID-19 Strains in United Kingdom and South Africa Trials

[Mary Wilson]

Mar 11, 2021 at 4:02 PM EST

• 100% protection against severe disease
• Final analysis in U.K. trial confirms 96% efficacy against original strain of COVID-19
• Efficacy against variants confirmed in U.K. and South Africa

GAITHERSBURG, Md., March 11, 2021 -- Novavax, Inc. (Nasdaq: NVAX), a biotechnology company developing next-generation vaccines for serious infectious diseases, today announced final efficacy of 96.4% against mild, moderate and severe disease caused by the original COVID-19 strain in a pivotal Phase 3 trial in the United Kingdom (U.K.) of NVX?CoV2373, the company?s vaccine candidate. The company also announced the complete analysis of its Phase 2b trial taking place in South Africa, with efficacy of 55.4% among the HIV- negative trial participants in a region where the vast majority of strains are B1.351 escape variants. Across both trials, NVX-CoV2373 demonstrated 100% protection against severe disease, including all hospitalization and death. Both studies achieved their statistical success criteria. Today?s final analyses build on the successful interim results announced in January 2021, adding substantially more COVID-19 cases and statistical power.
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United Kingdom Phase 3 Trial

The study enrolled more than 15,000 participants between 18-84 years of age, including 27% over the age of 65. The primary endpoint of the U.K. Phase 3 clinical trial is based on the first occurrence of PCR-confirmed symptomatic (mild, moderate or severe) COVID-19 with onset at least 7 days after the second study vaccination in serologically negative (to SARS-CoV-2) adult participants at baseline.

Efficacy was 96.4% (95% CI: 73.8, 99.5) against the original virus strain and 86.3% (95% CI: 71.3, 93.5) against the B.1.1.7/501Y.V1 variant circulating in the U.K (post hoc). The primary efficacy endpoint demonstrated an overall vaccine efficacy of 89.7% (95% CI: 80.2, 94.6). 106 cases were observed, with 10 in the vaccine group and 96 in the placebo group. NVX-CoV2373 was effective against severe disease: five severe[1] cases were observed in the study, and all occurred in the placebo group. Four of the five severe cases were attributed to the B.1.1.7/501Y.V1 variant. Fourteen days after dose 1, vaccine efficacy was 83.4% (95% CI: 73.6, 89.5).
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South Africa Phase 2b Trial

The South Africa trial was a randomized, observer-blinded, placebo-controlled Phase 2b clinical trial of NVX-CoV2373. One cohort evaluated efficacy, safety and immunogenicity in approximately 2,665 healthy adults. The second cohort evaluated safety and immunogenicity in approximately 240 medically stable, HIV-positive adults.

A complete analysis of vaccine efficacy among 147 PCR-positive cases (51 cases in the vaccine group and 96 in the placebo group) demonstrated an overall efficacy of 48.6% against predominantly variant strains (95% CI: 28.4, 63.1). The vast majority of cases circulating during the efficacy analysis were due to the B.1.351/501Y.V2 variant circulating in South Africa. All five cases of severe disease observed in the trial occurred in the placebo group. Among HIV-negative participants, 55.4% efficacy was observed (95% CI: 35.9, 68.9). The complete analysis shows that vaccine-induced protection began 14 days after dose 1 (42.7% 95% CI: 25.0, 56.3), although increased efficacy was observed 7 days after dose 2, the primary endpoint for the study.
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https://ir.novavax.com/news-release...s-efficacy-against-original-and?sf140129199=1