Antibody response after the third SARS-CoV-2 vaccine in solid organ transplant recipients and people living with HIV (COVERALL-2). Open Forum Infectious Diseases
Griessbach et al. aimed to assess the benefit and potential harm of a third SARS-CoV-2 vaccine for patients who were immunocompromised among those recruited from the Swiss HIV Cohort Study (SHCS) and the Swiss Transplant Cohort Study (STCS). This observational study entitled COVERALL-2 allowed for the inclusion of additional patients beyond the original randomized trial population in the COVERALL-1 study.
The study team collected blood samples before and 8 weeks after the third SARS-CoV-2 vaccination with either mRNA-1273 (Moderna) or BNT162b2 (Pfizer- BioNTech). The primary outcome was the proportion of participants showing an antibody response (Elecsys Anti-SARS-CoV-2 S test; threshold ≥100 U/mL) 8 weeks after the third SARS-CoV-2 vaccination. They also compared the proportion of patients who reached the primary outcome from basic immunization (the first and second vaccines) to the third vaccination.
Nearly all participants (97.2% [95% CI, 95.9%–98.6%], 564/580) had an antibody response. This response was comparable between mRNA-1273 (96.1% [95% CI, 93.7%–98.6%], 245/255) and BNT162b2 (98.2% [95% CI, 96.7%–99.6%], 319/325). Stratification by cohort showed that 99.8% (502/503) of people living with HIV and 80.5% (62/77) of recipients of solid organ transplants (SOT) achieved the primary endpoint. The proportion of patients with an antibody response in SOT recipients improved from the second vaccination (22.7%, 15/66) to the third (80.5%, 62/77).
In conclusion, this study shows a high proportion of patients who were immunocompromised had an antibody response after the third SARS-CoV-2 vaccination, and relatively few vaccine-related adverse events were reported. SOT recipients profited substantially in terms of an increased antibody response between the second and third doses. For patients with low humoral response, alternatives have to be explored. The new bivalent SARS-CoV-2 mRNA vaccines may represent a promising approach.