A systematic review and meta-analysis revealed that full vaccination of coronavirus vaccines is highly efficacious against alpha variants and moderately efficient against Delta, Gamma, and Beta variants. The booster vaccination is more efficient against Omicron and Delta variants. The mRNA vaccines appear to have greater vaccine effectiveness against Delta, Gamma, Beta, and Alpha variants over others.

Baoqi Zeng et al. aimed to offer an extensive outline of the efficiency profile of coronavirus vaccines against SARS-CoV-2 variants. Overall, 11 randomized controlled trials, 20 cohort studies, and 26 case-control studies that assessed vaccine effectiveness against variants of concern (Alpha, Beta, Gamma, Delta, or Omicron)  were encompassed. This analysis included 11 COVID-19 vaccines (HB02, CvnCoV, SCB-2019, BBIBP-CorV, CoronaVac, BBV152, NVX-CoV2373, Ad26.COV2.S, ChAdOx1, BNT162b2, and mRNA-1273).

Utilizing random-effects meta-analysis, calculation of the pooled estimates and 95% confidence intervals was done. Vaccine effectiveness was characterized as (1-estimate).  Full vaccination was efficient against Omicron, Delta, Gamma, Beta, and Alpha variants as depicted in Table 1:

Booster vaccination was more efficient against Omicron and Delta variants, as depicted in Table 2:

mRNA vaccines (mRNA-1273/BNT162b2) appeared to have greater vaccine effectiveness against variants of concern over others; profound correlations were seen between the type of vaccine (mRNA vaccines versus non-mRNA vaccines) and vaccine effectiveness.  Hence, COVID-19 vaccines yield high protection against COVID-19 variants of concern.