OBJECTIVES: As Canada’s public healthcare payers transition to planning COVID-19 vaccine programs in an endemic context, the question of the preferred mRNA vaccine persists. To inform this decision, this systematic literature review (SLR) and meta-analysis assessed the comparative effectiveness of the mRNA‑1273 versus BNT162b2 COVID-19 vaccines amongst Canadians.

METHODS: An SLR search was conducted in Medline, Embase, the Cochrane Database of Systematic Reviews (CDSR) and Cochrane Central Register of Controlled Trial (CENTRAL) for studies reporting COVID-19 outcomes with ≥ 2 doses of mRNA vaccines in Canadians aged ≥16 years, considering only English language publications from 2019 onwards. Outcomes of interest included SARS-CoV-2 infection, symptomatic SARS-CoV-2 infection, and severe SARS-CoV-2 infection. Random-effects meta-analysis models were used to pool risk ratios (RRs) across studies. Heterogeneity was evaluated using chi-squared testing. Certainty of evidence was assessed per the GRADE framework.

RESULTS: There were 11 non-randomized, real-world studies in Canadians aged ≥16 years included in the meta-analysis. Vaccination with mRNA-1273 was associated with lower risk of SARS-CoV-2 infection (mRNA‑1273: 8,369; BNT162b2: 27,864; RR: 0.68 [95% CI: 0.60–0.77]), symptomatic SARS-CoV-2 infection (mRNA‑1273: 2,683; BNT162b2: 10,922; RR: 0.74 [95% CI 0.71–0.77]), severe SARS-CoV-2 infection (mRNA‑1273: 482; BNT162b2: 1,227; RR: 0.90 [95% CI 0.73–1.11]) as compared to BNT162b2. There was considerable heterogeneity between studies for SARS-CoV-2 infection (I² =92%) and severe SARS-CoV-2 infection (I² =63.5%), except symptomatic SARS-CoV-2 infection (I²=0%). Results were generally consistent across subgroups (e.g., residents of long-term care homes, ≥50-year-olds, ≥3 doses [homologous or heterologous series]). Certainty of evidence across outcomes was rated as low (type 3) or very low (type 4), reflecting the lack of randomized-controlled trial data.

CONCLUSIONS: This meta-analysis of 11 observational studies demonstrated statistically significant lower risk of infections, including symptomatic infections, with the mRNA-1273 vaccine versus the BNT162b2 vaccine in Canadians aged ≥16 years.