Serial Interval Distribution of COVID-19 among Iranian Reported Confirmed Cases

Authors

  • Fariba Zare 1 1- Center for Health Related Social and Behavioral Sciences Research, Shahroud University of Medical Sciences, Shahroud, Iran.
  • Mohammad Hassan Emamian 2 2- Ophthalmic Epidemiology Research Center, Shahroud University of Medical Sciences, Shahroud, Iran.
  • Reza Chaman 3 3- Department of Epidemiology, School of Public Health, Shahroud University of Medical Sciences, Shahroud, Iran.
  • Marzieh Rohani-Rasaf 3 3- Department of Epidemiology, School of Public Health, Shahroud University of Medical Sciences, Shahroud, Iran.
  • Shahrbanoo Goli 3 3- Department of Epidemiology, School of Public Health, Shahroud University of Medical Sciences, Shahroud, Iran.
  • Solmaz Talebi 3 3- Department of Epidemiology, School of Public Health, Shahroud University of Medical Sciences, Shahroud, Iran.
  • Ali Hosseinzadeh 3 3- Department of Epidemiology, School of Public Health, Shahroud University of Medical Sciences, Shahroud, Iran.
  • Ahmad Khosravi 1,3* 1- Center for Health Related Social and Behavioral Sciences Research, Shahroud University of Medical Sciences, Shahroud, Iran, 3- Department of Epidemiology, School of Public Health, Shahroud University of Medical Sciences, Shahroud, Iran.

DOI:

https://doi.org/10.22100/ijhs.v7i4.824

Keywords:

COVID-19, Serial interval, Gamma distribution

Abstract

Type 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 (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.

Key words: COVID-19, Serial interval, Gamma distribution

References

1. Fine PE. The interval between successive cases of an infectious disease. American journal of epidemiology. 2003;158(11):1039-47.
2. Du J, Dong L, Wang T, Yuan C, Fu R, Zhang L, et al. Psychological symptoms among frontline healthcare workers during COVID-19 outbreak in Wuhan. General hospital psychiatry. 2020.
3. Khosravi A, Chaman R, Rohani-rasaf M, Zare F, Mehravaran S, Emamian M. The basic reproduction number and prediction of the epidemic size of the novel coronavirus (COVID-19) in Shahroud, Iran. Epidemiology and Infection. 2020;accepted.
4. Du Z, Xu X, Wu Y, Wang L, Cowling BJ, Meyers L. Serial Interval of COVID-19 among Publicly Reported Confirmed Cases. Emerging Infectious Diseases. 2020;26(6): 1341-3.
5. Aghaali M, Kolifarhood G, Nikbakht R, Mozafar Saadati H, Hashemi Nazari SS. Estimation of the Serial Interval and Basic Reproduction Number of COVID-19 in Qom, Iran, and Three Other Countries: A Data-Driven Analysis in the Early Phase of the Outbreak. Transboundary and Emerging Diseases. 2020;n/a(n/a).
6. Zhang W. Estimating the presymptomatic transmission of COVID19 using incubation period and serial interval data. medRxiv. 2020.
7. Nishiura H, Linton NM, Akhmetzhanov AR. Serial interval of novel coronavirus (COVID-19) infections. International journal of infectious diseases. 2020.

Downloads

Published

2021-07-24

Issue

Section

Articles