The efficacy and effectiveness of COVID-19 vaccines in Iran: a systematic review and meta-analysis

With the end of the COVID-19 pandemic, there is an increasing demand for comprehensive data on vaccine effectiveness disaggregated by country. Such information will provide insights into national immunization policy differences and lay the groundwork for future pandemic readiness plans. This study evaluates the efficacy and effectiveness of COVID-19 vaccines in Iran.

A systematic search was conducted in PubMed, Scopus, Web of Science, and Google Scholar up to February 1, 2025. Studies assessing COVID-19 vaccine effectiveness or efficacy in Iran without restrictions on variants or vaccine platforms were included in the systematic review. Meta-analysis using the random effects model was performed to estimate the pooled effectiveness of combined vaccination platforms against hospital admission and death outcomes.

Two randomized controlled trials (RCTs) and 11 observational studies were included in the systematic review, and five observational studies were included in the meta-analysis. Based on the meta-analysis, considering all vaccination platforms combined, the pooled effectiveness of 2-dose COVID-19 vaccines against hospital admission and death was 51.1% (21.8 to 69.5) and 55.7% (-1.5 to 80.7), respectively. Against infection, RCTs reported efficacies of 50.2% and 49.7%, while observational studies reported effectiveness ranging from 63.9% to 87.1% for different vaccines.

Vaccine effectiveness varied substantially across the studies, with unique patterns related to Iran's situation during the pandemic, including the high number of different deployed vaccines. The lack of sufficient studies and high heterogeneity between the included studies have limited the understanding of COVID-19 vaccines' effectiveness in Iran.