Sanofi, GSK single booster dose of COVID vaccine shows strong immune responses

Regulatory authorities require Phase 3 efficacy to be demonstrated in "naive" populations, i.e. participants who have never been infected by the COVID-19 virus (seronegative). The Phase 3 trial recruited most participants in Q3 2021, coinciding with a significant increase in the number of people infected by the COVID-19 virus globally due to the Delta variant. To provide the necessary data to regulatory authorities for the booster vaccine submission, the trial will continue to accrue the number of events needed for analysis, with results expected in Q1, 2022.

"These preliminary data show we have a strong booster candidate, whatever primary vaccine you have received." said Thomas Triomphe, Executive Vice President, Sanofi Pasteur. "This is consistent with our efforts to provide relevant responses to evolving public health needs. While pursuing a phase 3 trial is a challenge in a quickly shifting pandemic environment, we look forward to seeing the results to support submissions of our booster vaccine as quickly as possible."

Roger Connor, President of GSK Vaccines, added: "As the pandemic threat continues with the current dominant Delta variant and Omicron rapidly gaining ground, booster vaccines will continue to be needed to help protect people over time. The initial booster data are promising, and we await the phase III results to determine the next steps on making protein-based adjuvanted COVID-19 vaccines available."