Sanofi and GSK to seek regulatory authorization for COVID-19 vaccine.

The public health relevance of the refrigerator temperature-stable adjuvanted protein-based Sanofi-GSK vaccine is strongly supported by the induction of robust immune responses and a favorable safety profile in multiple settings. In participants who had received a primary series of an already authorized mRNA or adenovirus vaccine, the Sanofi-GSK booster vaccine induced a significant increase in neutralizing antibodies of 18- to 30-fold across vaccine platforms and age groups. When the Sanofi-GSK vaccine was used as a two-dose primary series followed by a booster dose, neutralizing antibodies increased 84- to 153-fold compared to pre-boost levels.

When used as a two-dose primary series, the Sanofi-GSK vaccine delivered robust levels of neutralizing antibodies, with GMTs reaching 3711 units. For comparison, a panel of sera from volunteers in the same age range who received two doses of an already approved and highly effective mRNA vaccine displayed a GMT of 1653 units, measured simultaneously in the same laboratory.

Data from the VAT08 efficacy study showed that two doses of Sanofi-GSK vaccine generated an efficacy of 57.9% (95% confidence interval [CI, 26.5, 76.7]) against any symptomatic COVID-19 disease in the seronegative population. The Sanofi-GSK vaccine provided 100% protection (0 vs 10 cases post-dose 1, 0 vs 4 cases post-dose 2) against severe disease and hospitalizations and 75% (3 vs 11 cases) efficacy against moderate-to-severe disease in seronegative populations. While sequencing is still in progress, early data indicate 77% efficacy against any Delta variant-associated symptomatic COVID-19 disease, in line with expected vaccine effectiveness.

Across both studies, the Sanofi-GSK vaccine was well-tolerated in younger and older adults with no safety concerns.