Seroconversion rate after primary vaccination with two doses of BNT162b2 versus mRNA-1273 in solid organ transplant recipients: a systematic review and meta-analysis

In the general population, the seroconversion rate after primary vaccination with two doses of anti-SARS-CoV-2 mRNA vaccine reaches nearly 100%, with significantly higher antibody titers after mRNA-1273 vaccination compared to BNT162b2 vaccination. Here, we performed a systematic review and meta-analysis to compare the antibody response after two-dose mRNA-1273 versus BNT162b2 vaccination in solid organ transplant (SOT) recipients. A systematic literature research was performed in Pubmed, Web of Science, and the Cochrane library and original research papers were included for a meta-analysis to calculate vaccine-specific seroconversion rates for each of the mRNA vaccines. Next, the pooled relative seroconversion rate was estimated. Six studies that described the development of antibodies against receptor-binding domain (RBD) and/or S1 subunit of the spike protein were eligible for meta-analysis. Two of them also reported antibody titers. The meta-analysis revealed lower seroconversion rates in SOT recipients vaccinated with two doses of BNT162b2 (45.2%; 95% confidence interval (CI) 32.5%-58.3%) than patients vaccinated with two doses of mRNA-1273 (60.4%; 95% CI 47.4%-72.7%. The relative seroconversion rate amounted 0.79 (95% CI 0.71-0.88). This systematic review and meta-analysis indicates that, in SOT recipients, higher seroconversion rates were observed after vaccination with mRNA-1273 compared to BNT162b2.