Type of manuscript: short reportIntroduction:
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 (R۰), 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-۱۹ using a Gamma distribution. Methods: To determine the serial interval, ۶۰ confirmed infected cases of
COVID-۱۹ (based on PCR test results) in February ۲۰th-May ۲۰th, ۲۰۲۰ were selected as the cases. For these cases, ۳۷ transmissions occurred. The data of the dates of the occurrence of primary and secondary symptoms were collected by referring to the
COVID-۱۹ surveillance system and interviewing the patientsResults: The findings showed that the median and mean of the serial interval were ۳.۰ and ۴.۵± ۳.۵ days. The findings showed that the median of the serial interval was ۳.۰ days (with the inter-quartile range of ۲.۰-۶.۰). The mean serial interval was ۴.۵± ۳.۵ days (۹۵% confidence interval: ۳.۱-۵.۵).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 ۷.۵ days.Key words: COVID-۱۹, Serial interval, Gamma distributionType of manuscript: short report Introduction:
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 (R۰), 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-۱۹ using a Gamma distribution. Methods: To determine the serial interval, ۶۰ confirmed infected cases of
COVID-۱۹ (based on PCR test results) in February ۲۰th-May ۲۰th, ۲۰۲۰ were selected as the cases. For these cases, ۳۷ transmissions occurred. The data of the dates of the occurrence of primary and secondary symptoms were collected by referring to the
COVID-۱۹ surveillance system and interviewing the patients Results: The findings showed that the median and mean of the serial interval were ۳.۰ and ۴.۵± ۳.۵ days. The findings showed that the median of the serial interval was ۳.۰ days (with the inter-quartile range of ۲.۰-۶.۰). The mean serial interval was ۴.۵± ۳.۵ days (۹۵% confidence interval: ۳.۱-۵.۵). 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 ۷.۵ days. Key words: COVID-۱۹, Serial interval, Gamma distribution