Effectiveness of COVID-19 Vaccines in Mahabad, Iran: A Cohort Study

Document Type : Original Articles

Authors

1 Department of Epidemiology and Biostatistics, School of Medicine, Urmia University of Medical Sciences, Urmia, Iran.

2 Assistant Professor of Epidemiology Department of Epidemiology and Biostatistics School Of Medicine Urmia University Of Medical Sciences Urmia , Iran.

10.32592/ARI.2025.80.3.615

Abstract

The COVID-19 pandemic has shown that infectious diseases can become serious crises, emphasizing the importance of vaccination as the best way to prevent such outbreaks. The aim of study was to examine how well COVID-19 vaccines work in the northwestern region of Iran, city of Mahabad.This retrospective cohort study compared 1077 vaccinated employees of the Mahabad city health department (exposed group) with 1338 unvaccinated employees from other departments (unexposed group). Demographic details, vaccination dates, types, and outcomes were extracted from the local health system. Data on cases came from the disease unit, while hospitalization was retrieved from the Medical Care Monitoring Center (MCMC). Attributable fractions for the exposed group and relative risks with 95% confidence intervals were calculated for each vaccine dose, stratified by sex, age group, and exposure level. Data analysis was conducted using STATA16, with a p-value < 0.05 considered statistically significant.The overall efficacy of COVID-19 vaccines in preventing the disease is 51%, with a 26% effectiveness in averting hospitalization. Stratifying by vaccine type, AstraZeneca exhibits an 81% efficacy (95% CI: 0.61–0.91) in preventing infection, followed by Sputnik at 41% (95% CI: 0.086–0.62) and Sinopharm-Baharat at 10% (95% CI: 0.50–0.46). Similarly, in preventing hospitalization, AstraZeneca demonstrates a 79% efficacy (95% CI: 0.083–0.95), Sputnik at 29% (95% CI: 0.77–0.71), and Sinopharm–Bharat at 44% (95% CI: 0.63–0.81). Notably, effectiveness in preventing both disease and hospitalization is higher in men than women. AstraZeneca vaccine emerges as the most effective in preventing both disease and hospitalization, followed by Sputnik with optimal efficacy. Analyzing vaccine effectiveness across age groups reveals the lowest efficacy in individuals below 30 years old, while the highest efficacy is observed in the age group above 51 years. Despite challenges in vaccine selection and timely administration in Iran, our findings demonstrate that three doses of COVID-19 vaccines achieve an effectiveness exceeding 75% for preventing hospitalization and death, underscoring the vital role of vaccination as a primary preventive measure against infectious disease outbreaks. This reinforces the importance of proactive preparation and investment in robust vaccination programs for optimal epidemic control.

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Archives of Razi Institute
Volume 80, Issue 3
May and June 2025
Pages 615-622

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