Sanofi and GSK COVID-19 Vaccine Demonstrates 100% Efficacy Against Severe Disease and Hospitalizations

The companies plan to seek regulatory authorization for the vaccine both in the US and Europe.

Sanofi and GSK reported today their Sanofi-GSK COVID-19 vaccine showed 100% efficaciousness against severe disease and hospitalizations. In addition, the companies reported their vaccine was 75% efficacy against moderate or severe COVID-19 disease, and 57.9% efficacy against any symptomatic disease.

“We’re very pleased with these data, which confirm our strong science and the benefits of our COVID-19 vaccine,” Thomas Triomphe, executive vice president, Sanofi Vaccines, said. “We also observed robust efficacy of the vaccine as a primary series in today’s challenging epidemiological environment. No other global phase 3 efficacy study has been undertaken during this period with so many variants of concern, including Omicron, and these efficacy data are similar to the recent clinical data from authorized vaccines.”

VAT08 Phase 3 Trial

This trial has been evaluating a 10µg antigen formulation of the SARS-CoV-2 adjuvanted recombinant protein-based vaccine for efficacy, immunogenicity and safety compared to a placebo. The first stage of the trial assessed the efficacy of a vaccine formulation containing the spike protein against the original D614 (parent) virus in more than 10,000 participants >18 years of age, randomized to receive 2 doses of 10µg vaccine or placebo at day 1 and day 22 across sites in the US, Asia, Africa, and Latin America.

Data from the VAT08 efficacy study showed that 2 doses of the 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.

Although there is sequencing still being performed, early data indicates a 77% efficacy against any Delta variant-associated symptomatic COVID-19 disease.

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 2-dose primary series followed by a booster dose, neutralizing antibodies increased 84- to 153-fold compared to pre-boost levels.

Potential Benefits and Submitting Data to Federal Regulators

The Sanofi-GSK vaccine can be stored in a refrigerator temperature-stable environment, which may make it attractive to developing countries who have cold storage issues. “The evolving epidemiology of COVID-19 demonstrates the need for a variety of vaccines,” Roger Connor, president of GSK Vaccines, said.

For those people who have allergies associated with the m-RNA vaccines or the potential myocarditis risks in young males, this vaccine offers another alternative to the current vaccines on the market. “Our adjuvanted protein-based vaccine candidate uses a well-established approach that has been applied widely to prevent infection with other viruses including pandemic flu," Connor said. "We are confident that this vaccine can play an important role as we continue to address this pandemic and prepare for the post-pandemic period.”

Sanofi and GSK are planning to submit their vaccine data to both the Food and Drug Administration and European Medicines Agency. No timeline for the submissions was announced.