Background There are some concerns about the effectiveness of the inactivated and vector-based vaccines against SARS-CoV-2 in the real-world settings with the emergence of new mutations, especially variants of concern. Data derived from administrative repositories during mass-vaccination campaigns or programs are of interest to study vaccine effectiveness (VE). Methods Using 4-repository administrative data linkage, we conducted a historical cohort study on a target population of 1,882,148 inhabitants aged at least 18 years residing in Southern Iran. Results We estimated 71.9% [95% CI: 70.7-73.1%], 81.5% [95% CI: 79.5-83.4%], 67.5% [95% CI: 59.5-75.6%], and 86.4% [95% CI: 84.1-88.8%] hospital admission reduction for those who received the full vaccination schedule of BBIBP-CorV (Sinopharm), ChAdOx1-S/nCoV-19 vaccine (AZD1222, Oxford–AstraZeneca), rAd26-rAd5 (Gam-COVID-Vac, Sputnik V), and BIV1-CovIran (COVIran Barekat) vaccines, respectively. A high reduction in mortality – at least 85% – was observed in all age subgroups of fully immunized population. Conclusion The pragmatic implementation of a vaccination plan including all available vaccine options in the Iranian population was associated with a significant reduction in COVID-19 detected infections as well as hospital admissions and deaths associated with COVID-19.

Background: There are some concerns about the effectiveness of the inactivated and vector-based vaccines against SARS-CoV-2 in the real-world settings with the emergence of new mutations, especially variants of concern. Data derived from administrative repositories during mass-vaccination campaigns or programs are of interest to study vaccine effectiveness (VE). Methods: Using 4-repository administrative data linkage, we conducted a historical cohort study on a target population of 3,628,857 inhabitants aged at least 18 years residing in Southern Iran. Results: We estimated 71.9% [95% CI: 70.7-73.1%], 81.5% [95% CI: 79.5-83.4%], 67.5% [95% CI: 59.5-75.6%], and 86.4% [95% CI: 84.1-88.8%] hospitalization reduction for those who received the full vaccination schedule of BIBP-CorV, ChAdOx1-S/nCoV-19, rAd26-rAd5, and BIV1-CovIran vaccines, respectively. A high reduction in mortality, at least 85%, was observed in all age subgroups of fully immunized population. Conclusion: The pragmatic implementation of a vaccination plan including all available vaccine options in the Iranian population was associated with a significant reduction in documented COVID-19 infection, hospitalization, and death associated with COVID-19.

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