The Dynamic Effective Reproductive Number of COVID-19  during the Epidemic in Iran

Amin  Doosti-Irani; Saiedeh   Haji-Maghsoudi; Aliakbar  Haghdoost; Sana  Eybpoosh; Ehsan  Mostafavi; Manoochehr  Karami; Hossein  Mahjub

doi:10.18502/ijph.v51i4.9250

Amin Doosti-Irani Department of Epidemiology, School of Public Health, Hamadan University of Medical Sciences, Research Center for Health Sci-ences, Hamadan Iran
Saiedeh Haji-Maghsoudi Department of Epidemiology and Biostatistics, School of Public Health, Kerman University of Medical Sciences, Kerman, Iran
Aliakbar Haghdoost Department of Epidemiology and Biostatistics, School of Public Health, HIV/STI Surveillance Research Center, Institute for Fu-tures Studies in Health, Kerman University of Medical Sciences, Kerman, Iran
Sana Eybpoosh Research Centre for Emerging and Reemerging Infectious Diseases, Pasteur Institute of Iran, Tehran, Iran
Ehsan Mostafavi Research Centre for Emerging and Reemerging Infectious Diseases, Pasteur Institute of Iran, Tehran, Iran
Manoochehr Karami Department of Epidemiology, School of Public Health and Safety, Shahid Beheshti University of Medical Sciences, Tehran, Iran
Hossein Mahjub Department of Biostatistics, School of Public Health, Research Center for Health Sciences, Hamadan University of Medical Sciences, Hamadan, Iran

DOI: https://doi.org/10.18502/ijph.v51i4.9250

Keywords: COVID-19; Basic reproduction number; Effective reproduction number; Iran

Abstract

Background: We aimed to determine the generation time, the best model for estimating reproduction number (R), and to estimate the basic reproduction number (R₀) and effective reproduction number (R_t) for COVID-19 in Iran.

Methods: We used the daily incidence cases of COVID-19, hospitalized due to a probable diagnosis of COVID-19 from 19 February 2020 to 17 November 2020 in Iran. Four models, including maximum likelihood (ML), exponential growth (EG), time-dependent (TD), sequential Bayesian (SB) were evaluated. The weekly reproduction number with a 95% confidence interval (CI) was calculated.

Results: TD model shows the best fit compared to other models for estimating reproduction number in Iran. The R₀ in Iran in the first week of the epidemic, leading up to 21 February 2020 was 7.19, 95% CI: 5.56, 9.00. The lowest value for the R_t was equal to 0.77 between 3 to 10 March 2020 and 4 to 11 December 2020. From 11 June 2020 up to13 August 2020, the R_t was more than one but after then to 24 September 2021 was less than one.

Conclusion: TD model was the best fit for estimating the R in Iran. The worst situation of the epidemic in Iran was related to the weeks leading up to 26 February 2020 and 28 October 2020, and better status was related to the weeks leading up to 10 March 2020 and 11 December 2020.