Sanofi-GSK COVID-19 Booster More Protective Against Omicron Than Pfizer-BioNTech

The currently approved COVID-19 vaccines are highly effective against severe or fatal infection, and this protection increases even more with a booster dose. However, the highly contagious Omicron variant is causing an unprecedented rate of breakthrough infections in people vaccinated against COVID-19. Thus, the race is on to develop a vaccine that can protect against Omicron and other variants of concern.

Today, the global healthcare company Sanofi announced positive results from 2 trials for their next-generation COVID-19 booster candidate. The booster is modeled on the Beta variant antigen, and features an adjuvant from GlaxoSmithKline (GSK).

“COVID-19 keeps evolving and the combination of emergence of variants and waning immunity is likely to lead to the need for additional booster shots, at least in some populations,” said Thomas Triomphe, the executive vice president of Sanofi Vaccines. “The Beta variant expresses similar mutations across multiple variants of concern, including Omicron, making it a strong vaccine candidate to confer broad protection against multiple strains of COVID-19.”

Sanofi reported data from 2 clinical trials, VAT02 Cohort 2 and COVIBOOST VAT013. In the former, phase 3 study, the booster candidate significantly raised antibody titers above baseline against numerous variants of concern. Antibodies were boosted 15-fold against the D614 parent virus and 30-fold against the Beta variant in a cohort of adults with prior mRNA COVID-19 vaccinations.

Most notably, there was a 40-fold increase in antibody titers against the Omicron BA.1 variant. Compared to the booster vaccine based on the original parent COVID-19 virus, the Sanofi-GSK booster candidate elicited double the number of neutralizing antibodies against Omicron BA.1 and BA.2.

The independently conducted COVIBOOST VAT013 study found Sanofi-GSK’s booster generated more neutralizing antibody titers than Pfizer-BioNTech’s COVID-19 vaccine booster. The Pfizer-BioNTech booster and the Sanofi-GSK first-generation booster both target the original D614 strain, and this next-generation booster candidate outperformed them both.

The COVIBOOST VAT013 study was conducted by the Assistance Publique – Hôpitaux de Paris (AP-HP) and included 247 participants. The Sanofi-GSK booster candidate was well-tolerated, with less than 4% of VAT02 study patients reporting Grade 3 reactions, all of which were transient and non-severe. The trial participants were all previously vaccinated against COVID-19 with a Pfizer-BioNTech primary series.

All 3 tested booster vaccines created neutralizing antibodies against the Omicron BA.1 variant. Between study days 0-15, the proportion of patients with at least a 10-fold increase in neutralizing antibody titers was 76.1% for the Sanofi-GSK next-generation booster, 63.2% for the Pfizer-BioNTech D614 booster, and 55.3% for the first-generation Sanofi-GSK D614 booster.

“Seeing the cross-neutralization data from the independent AP-HP study, we believe this next-generation booster could have an important role to play for public health vaccination campaigns,” Triomphe said. “We look forward to submitting these data to global regulatory authorities.”

These data are expected to be submitted within the next few weeks, with hopes that the booster candidate will be available later this year. Sanofi and GSK shared that they designed this next-generation booster with regards to ongoing regulatory reviews of their first-generation vaccine.