This multicenter randomized controlled trial embedded in the Swiss HIV Cohort Study and the Swiss Transplant Cohort Study provides crucial information about the efficacy and safety of the mRNA SARS-CoV-2 vaccines.

After the approval of the SARS-CoV-2 vaccines, evidence on the efficacy and safety of bivalent mRNA-vaccines in persons with different degrees of immunosuppression was very limited. Therefore, we nested within the Swiss HIV Cohort study (SHCS) and the Swiss Transplant Cohort Study (STCS) the COrona VaccinE tRiAL pLatform (COVERALL). This trial platform provided rapid patient recruitment, efficient and cost-saving data collection, and  a highly flexible and adaptive study design, which was key given the rapidly changing circumstances during the COVID-19 pandemic. Within the first two trials we could show that (i) patients living with HIV already had a good antibody response after the basic immunization (with two doses of either Moderna or the Pfizer-BioNTech.  vaccine), and (ii) that in terms of antibody response, solid organ transplant patients strongly benefited from a third dose of the SARS-CoV-2 vaccine.