Author/Authors :
Zare, Fariba Center for Health Related Social and Behavioral Sciences Research - Shahroud University of Medical Sciences, Shahroud, Iran , Emamian, Mohammad Hassan Ophthalmic Epidemiology Research Center - Shahroud University of Medical Sciences, Shahroud, Iran , Chaman, Reza Department of Epidemiology - School of Public Health - Shahroud University of Medical Sciences, Shahroud, Iran , Rohani-Rasaf, Marzieh Department of Epidemiology - School of Public Health - Shahroud University of Medical Sciences, Shahroud, Iran , Goli, Shahrbanoo Department of Epidemiology - School of Public Health - Shahroud University of Medical Sciences, Shahroud, Iran , Talebi, Solmaz Department of Epidemiology - School of Public Health - Shahroud University of Medical Sciences, Shahroud, Iran , Hosseinzadeh, Ali Department of Epidemiology - School of Public Health - Shahroud University of Medical Sciences, Shahroud, Iran , Khosravi, Ahmad Department of Epidemiology - School of Public Health - Shahroud University of Medical Sciences, Shahroud, Iran
Abstract :
Background: Serial interval refers to the average time between of the
onset of the symptoms of two successive cases. Serial interval
distribution can be used for the calculation of the basic reproduction
number (R0), transmission rate, and study of an epidemic trend. This
study aims to investigate the mean, standard deviation, and distribution
of serial interval among the confirmed cases of COVID-19 using a
Gamma distribution.
Methods: To determine the serial interval, 60 confirmed infected cases
of COVID-19 (based on PCR test results) in February 20th-May 20th,
2020 were selected as the cases. For these cases, 37 transmissions
occurred. The data of the dates of the occurrence of primary and
secondary symptoms were collected by referring to the COVID-19
surveillance system and interviewing the patients
Results: The findings showed that the median and mean of the serial
interval were 3.0 and 4.5±3.5 days. The findings showed that the
median of the serial interval was 3.0 days (with the inter-quartile range
of 2.0-6.0). The mean serial interval was 4.5±3.5 days (95% confidence
interval: 3.1-5.5).
Conclusions: Our report showed a shorter period for a serial interval
less than the previous reported interval in China. It seems that
regarding the shorter serial interval reported in this study, the basic
reproduction numbers reported by the first papers published in Iran
have been overestimated regarding the serial interval of 7.5 days.
