The primary objectives of the study are:

To assess the safety profile of all participants in each age group and in each study intervention group.

To assess the neutralizing antibody profile 14 days after the last vaccination in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-naïve adults in each study intervention group.

The secondary objectives of the study are:

To assess the neutralizing antibody profile in SARS-CoV-2 naïve participants at pre-defined time points during the study.

To assess the neutralizing antibody profile in SARS-CoV-2 non-naïve participants at pre-defined time points during the study.

To assess the binding antibody profile in SARS-CoV-2 naïve and non-naïve participants at pre-defined time points during the study.

To describe the occurrences of laboratory-confirmed symptomatic COVID-19 in all participants in each study intervention group.

To describe the occurrences of serologically-confirmed SARS-CoV-2 infection in each study intervention group.

Interim Results

Sanofi and GSK announce the Phase 2 interim results showed 95% to 100% seroconversion following a second injection in all age groups (18 to 95 years old) and across all doses, with acceptable tolerability and with no safety concerns.

Overall, the vaccine candidate elicited strong neutralizing antibody levels that were comparable to those generated by natural infection, with higher levels observed in younger adults (18 to 59 years old).

After a single injection, high neutralizing antibody levels were generated in participants with evidence of prior SARS-CoV-2 infection, suggesting strong potential for development as a booster vaccine.