Sanofi and GSK initiate Phase 3 study of COVID-19 vaccine candidate

May 28, 2021

Sanofi and GlaoSmithKline (GSK) started enrollment in their Phase 3 clinical study of their adjuvanted recombinant-protein COVID-19 vaccine candidate, the companies said in a news release.

The global randomized, double-blind, placebo-controlled Phase 3 study will include more than 35,000 volunteers 18 years and older from numerous countries, including sites in the United States, Asia, Africa, and Latin America.

The primary endpoint of the study is the prevention of symptomatic COVID-19 in SARS-CoV-2 naïve adults, with secondary endpoints being the prevention of severe COVID-19 disease and prevention of asymptomatic infection.

In a two-stage approach, the study will initially investigate the efficacy of a vaccine formulation targeting the original D.614 virus (Wuhan), while a second stage will evaluate a second formulation targeting the B.1.351 (South African) variant. The companies also said the design of the Phase 3 study, conducted across a broad diversity of geographies, also allows evaluation of the efficacy of the candidate against a variety of circulating variants.

The Phase 3 study follows the interim Phase 2 results which showed that the adjuvanted recombinant COVID-19 vaccine candidate achieved high rates of neutralizing antibody responses in all adult age groups, with 95 to100% seroconversion rates. After a single injection, high neutralizing antibody levels were also generated in participants with evidence of prior SARS-CoV-2 infection, suggesting strong potential for development as a booster vaccine.

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