The following is a summary of “Antibody and T-Cell Response to Bivalent Booster SARS-CoV-2 Vaccines in People With Compromised Immune Function: COVERALL-3 Study,” published in the June 2024  issue of Infectious Disease by Amstutz et al.

Bivalent mRNA vaccines combine protection against SARS-CoV-2 variants with a targeted response to a new variant.

Researchers conducted a retrospective study investigating the immune response to bivalent mRNA vaccines in previously vaccinated participants from the Swiss HIV Cohort Study (SHCS) and the Swiss Transplant Cohort Study (STCS).

They included participants from the SHCS and STCS who met eligibility criteria and received routine vaccinations with approved bivalent mRNA SARS-CoV-2 vaccines (either mRNA-1273.214 or BA.1-adapted BNT162b2). Blood samples were collected at four time points at baseline, 4 weeks, 8 weeks, and 6 months post-vaccination. The two critical aspects of the immune response were analyzed: the participants proportion with an antibody response to the spike protein exceeding 1642 units/ml, which suggests protection against SARS-CoV-2 infection, and T-cell response (including mean concentrations) in a participants subsample. Additionally, results were stratified by cohort (SHCS vs. STCS) and demographic characteristics.

The result showed that in SHCS, only 87% (96/112) displayed baseline anti-spike antibody concentrations ≥1642, almost reaching 100% during follow-ups. Among participants of STCS, 58% (35/60) had baseline antibodies ≥1642, increasing to 80% at 6 months. All participants except for lung transplant exhibited a five-fold increase in geometric mean antibody concentrations at four weeks, which decreased by half at six months. The T-cell responses were positive at baseline in 96% (26/27) of participants of SHCS and 36% (16/45) of participants of STCS, with a moderate increase to 53% at six months. Some participants reported severe AEs or side effects, as well as SARS-CoV-2 infections.

Investigators concluded bivalent mRNA vaccines effectively boosted antibody response in HIV and patients with organ transplants, whereas recipients with lung transplants showed a slower response.

Source: academic.oup.com/jid/advance-article/doi/10.1093/infdis/jiae291/7689653