Background and aims: Various methods have been employed globally to prevent the spread of COVID-19. However, the effectiveness of vaccination in reducing COVID-19 infections requires further investigation. This study aimed to assess the impact of the national vaccination program on the trend of COVID-19 infections in Iran, utilizing an interrupted time series model from February 19, 2020, to March 20, 2022.
Methods: In this quasi-experimental study, we employed a regression method based on Newey's Ordinary Least Squares to analyze daily data on COVID-19 infections in Iran, applying the interrupted time series model.
Results: The daily trends of COVID-19 infections were analyzed on two specific dates: September 23, 2021, and November 22, 2021. Prior to the implementation of the vaccination program, the trend of new cases was on the rise on both dates (p<0.0001). However, following the intervention, there was a statistically significant decrease in new cases (p<0.0001).
Conclusion: National vaccination campaigns against COVID-19 have significantly contributed to reducing the incidence of the disease. It is crucial to continue these vaccination efforts to control the spread of COVID-19.