COVID-19 Evidence Alerts
from McMaster PLUSTM

Current best evidence for clinical care (more info)

Treatment Verleye A, Wijtvliet V, Abrams S, et al. Seroconversion rate after primary vaccination with two doses of BNT162b2 versus mRNA-1273 in solid organ transplant recipients: a systematic review and meta-analysis. Nephrol Dial Transplant. 2022 Jul 26;37(8):1566-1575. doi: 10.1093/ndt/gfac174.
PICO Terms
anti-RBD IgG; anti-receptor-binding domain IgG (O) Comirnaty; Pfizer vaccine; BNT162b2; BioNTech/Fosun Pharma; mRNA (I/C) fully vaccinated (I/C) immunogenicity (O) SARS-CoV-2 spike protein-binding antibodies (O) seroconversion (O) Spikevax; Moderna vaccine; mRNA-1273 SARS-CoV-2; ModernaTX; mRNA (I/C) transplant (P) vaccine effectiveness (O)

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.

Discipline / Specialty Area Score
Internal Medicine
Infectious Disease
Comments from MORE raters

Gastroenterology rater

The final paragraph is salient, for much has been made of antibody response to vaccination as a surrogate marker of vaccine efficacy. This may or may not be appropriate. The authors state: "the seroconversion rate appeared to be higher after mRNA-1273 vaccination versus BNT162b2 vaccination in SOT recipients." The authors then state: "Future studies are needed to assess whether these differences are confirmed after third-dose vaccination and whether they also associated with a better protection against severe disease, hospitalization and/or mortality."

Gastroenterology rater

There is concern with desensitization regarding Covid and vaccinations, but this a clinically relevant article for which all physicians should be aware.

Nephrology rater

I believe both vaccines are efficacious but if one is superior, that would be good to know. Mortality in transplant recipients is high, but is improving with multiple boosters.

Nephrology rater

This meta-analysis/systematic review appears to confirm what we already believed to be true: mRNA vaccines against Covid are more effective than other vaccines in recipients of solid organ transplants.