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

Abstract

Background: In the general population, the seroconversion rate after primary vaccination with two doses of an anti-severe acute respiratory syndrome coronavirus 2 messenger RNA (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.

Methods: A systematic literature review was performed using 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.

Results: Eight studies that described the development of antibodies against receptor-binding domain (RBD) and/or spike protein were eligible for meta-analysis. Two of these studies also reported antibody titers. The meta-analysis revealed lower seroconversion rates in SOT recipients vaccinated with two doses of BNT162b2 {44.3% [95% confidence interval (CI) 34.1-54.7]} as compared with patients vaccinated with two doses of mRNA-1273 [58.4% (95% CI 47.2-69.2)]. The relative seroconversion rate was 0.795 (95% CI 0.732-0.864).

Conclusions: This systematic review and meta-analysis indicates that in SOT recipients, higher seroconversion rates were observed after vaccination with mRNA-1273 compared with BNT162b2.

Keywords: SARS-CoV-2/COVID-19; antibody response; mRNA vaccines; meta-analysis; solid organ transplant recipients.

Graphical Abstract

Figure 1:

Flow diagram of study selection. Source: Page MJ, McKenzie JE, Bossuyt PM et al. The PRISMA 2020 statement: an updated guideline for reporting systematic reviews. BMJ 2021; 372: n71.

Figure 2:

Study-specific and pooled estimates for the seroconversion rate after two-dose mRNA vaccination with (A) BNT162b2 or (B) mRNA-1273 based on RE meta-analysis models and relying on the IV method. Box sizes in the forest plots are proportional to the weight assigned to each study. Limits of the displayed intervals are defined as 95% CIs. Eight studies calculated the seroconversion rates in SOT recipients after two-dose BNT162b2 vaccination (n = 956), (A) resulting in a pooled seroconversion rate of 44.3% (95% CI 34.1–54.7). The same eight studies also described seroconversion rates in SOT recipients after two-dose mRNA-1273 vaccination (n = 877), (B) resulting in a pooled seroconversion rate of 58.4% (95% CI 47.2–69.2). df, degrees of freedom; I², inconsistency index.

Figure 3:

Meta-analytic result for the relative seroconversion rate (BNT162b2 versus mRNA-1273) based on an RE meta-analysis model and relying on the IV method. Seroconversion rates appeared to be significantly lower in patients vaccinated with two doses of BNT162b2 than in patients vaccinated with two doses of mRNA-1273 [79.5% (95% CI 73.2–86.4)].