Sanofi’s SARS-CoV-2 adjuvanted recombinant protein-based vaccine (COVID-19 candidate vaccine), developed in collaboration with GSK, has been administered to 440 adults in a first trial-a phase 1/2 trial (VAT00001).1 The first trial assessed the safety of the candidate vaccine and its capability to induce an immune response to help identify an optimal vaccine dose. Interim results from this trial showed a lower than expected antibody response to the vaccine, especially in individuals aged 60 years and older, in combination with a higher than expected reactogenicity.
Based on these observations, it is necessary to assess optimized antigen formulations to select a formulation that will progress to the next clinical steps. This is the objective of a phase 2 trial (VAT00002).2
Our phase 2 trial
This trial will assess the reactogenicity and safety of three different antigen concentrations combined with a set dose of AS03 adjuvant, as well as their capacities to induce immune responses.
The trial will be conducted in the US and Honduras and will include a total of 720 participants-one half will be 18-59 years of age and the other half 60 years of age or older.
To participate in this new phase 2 trial, volunteers must be 18 years old or older, willing, and able to attend all trial visits and perform medical procedures. Participants with high-risk medical conditions or those with a previous history of COVID-19 will be eligible to participate in the trial. Participants’ eligibility will be tested at the start of the trial.
Individuals currently participating in another trial, or who have previously received a vaccine against COVID-19, cannot take part in the trial. At this stage of the vaccine development, women who are pregnant or breastfeeding are also not yet eligible.
Eligible volunteers will be assigned randomly to receive one out the three vaccine formulations. There is no placebo in this trial.
Benefits and risks
The full benefit and risks of these candidate vaccine formulations are currently not completely understood. This trial is fundamental to determine the impact of a vaccine candidate that has the potential to help control the pandemic and reduce both the individual and public health burdens of COVID-19 illness and SARS-CoV-2 infections.