On Feb. 23, 2022, Sanofi and GSK  announced that they planned to submit data from both their booster and Phase 3 efficacy trials as the basis for regulatory applications for a COVID-19 vaccine.

The public health relevance of the refrigerator temperature-stable adjuvanted protein-based Sanofi-GSK vaccine was 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 (see Figures 1a and 1b for details).

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.