Evaluation of the COVID-19 vaccine effectiveness on the outcomes of COVID 19 disease in Iran: a test-negative case-control study

Front Immunol. 2024 Aug 20:15:1420651. doi: 10.3389/fimmu.2024.1420651. eCollection 2024.

Abstract

Introduction: This study measures the COVID-19 vaccine effectiveness (CVE) against hospital admission and severe COVID-19.

Methods: This study is a test-negative case-control design using data from eight provinces in April, 2021 until March, 2022. The individuals were classified as cases and controls based on the results of the RT-PCR test for SARS-CoV-2 and matched based on the timing of the test being conducted as well as the timing of hospital admission. The measure of association was an odds ratio (OR) by univariate and multiple logistic regression. The multiple logistic regression has been carried out to take confounding factors and potential effect modifiers into account. The CVE was computed as CVE = (1 - OR)*100 with 95% confidence interval.

Results: Among 19314 admitted patients, of whom 13216 (68.4%) were cases and 6098 (31.6%) were controls, 1313 (6.8%) died. From total, 5959 (30.8%) patients had received the vaccine in which one, two, and booster doses were 2443 (12.6%), 2796 (14.5٪), and 720 (3.7٪), respectively. The estimated adjusted effectiveness of only one dose, two doses and booter vaccination were 22% (95% CI: 14%-29%), 35% (95% CI: 29%-41%) and 33% (95% CI: 16%-47%), respectively. In addition, the adjusted vaccine effectiveness against severe outcome was 33% (95% CI: 19%- 44%), 34% (95% CI: 20%- 45%) and 20% (95% CI: -29%- 50%) for those who received one, two and booster vaccinations, respectively.

Conclusion: Our study concluded that full vaccination, though less effective compared to similar studies elsewhere, decreased hospital admissions and deaths from COVID-19 in Iran, particularly during the Delta variant period, with an observed decline during the Omicron variant dominance.

Keywords: COVID-19; Iran; death; hospital admission; test-negative case-control; vaccine effectiveness.

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • COVID-19 Vaccines* / administration & dosage
  • COVID-19 Vaccines* / immunology
  • COVID-19* / epidemiology
  • COVID-19* / immunology
  • COVID-19* / mortality
  • COVID-19* / prevention & control
  • Case-Control Studies
  • Female
  • Hospitalization / statistics & numerical data
  • Humans
  • Iran / epidemiology
  • Male
  • Middle Aged
  • SARS-CoV-2* / immunology
  • Vaccination
  • Vaccine Efficacy*
  • Young Adult

Substances

  • COVID-19 Vaccines

Grants and funding

The author(s) declare financial support was received for the research, authorship, and/or publication of this article. The study protocol underwent review, acceptance, and funding by the Eastern Mediterranean Regional Office (EMRO), for which we are sincerely appreciative of the support extended both prior to and throughout the study. Furthermore, the final report underwent scrutiny by EMRO’s technical team, and all data were meticulously verified and reanalyzed by MMGH Consulting. This research was supported by the World Health Organization (WHO) under reference number 2022/1240954-0. The purchase order associated with this funding is 202872118, and the unit reference is UHC/HSD/WCO Iran. The authors would like to acknowledge the financial support provided, which enabled the successful completion of this study.