Nine-month Trend of Time-Varying Reproduction Numbers of COVID-۱۹ in West of Iran

Background: The basic reproduction number (R۰) is an important concept in infectious diseaseepidemiology and the most important parameter to determine the transmissibility of a pathogen.This study aimed to estimate the nine-month trend of time-varying R of COVID-۱۹ epidemic usingthe serial interval (SI) and Markov Chain Monte Carlo in Lorestan, west of Iran.Study design: Descriptive study.Methods: This study was conducted based on a cross-sectional method. The SI distribution wasextracted from data and log-normal, Weibull, and Gamma models were fitted. The estimation oftime-varying R۰, a likelihood-based model was applied, which uses pairs of cases to estimaterelative likelihood.Results: In this study, Rt was estimated for SI ۷-day and ۱۴-day time-lapses from ۲۷ February-۱۴November ۲۰۲۰. To check the robustness of the R۰ estimations, sensitivity analysis was performedusing different SI distributions to estimate the reproduction number in ۷-day and ۱۴-day timelapses.The R۰ ranged from ۰.۵۶ to ۴.۹۷ and ۰.۷۶ to ۲.۴۷ for ۷-day and ۱۴-day time-lapses. Thedoubling time was estimated to be ۷۵.۵۱ days (۹۵% CI: ۷۰.۴۱, ۸۱.۴۱).Conclusions: Low R۰ of COVID-۱۹ in some periods in Lorestan, west of Iran, could be an indicationof preventive interventions, namely quarantine and isolation. To control the spread of the disease,the reproduction number should be reduced by decreasing the transmission and contact rates andshortening the infectious period.

کلیدواژه ها:

Basic reproduction number ، COVID-۱۹ ، Transmissibility Measures ، Disease Transmission ، Infectious ، Iran