Iranshahr University of medical sciences Scientific Journal of Medical Sciences 2783-4921 2 3 2023 09 01 Basic Reproduction Number of COVID-19 in Southeast Iran 103 108 EN E. Rezabeigi-Davarani N. Nasiri B. Kermani M. Mohammadkhani M. Nakhaeizadeh R. Faryabi V. Meshayekhi S. Daneshi Journal Article 2023 03 17 2023 08 17 Aims: COVID-19 is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) of the coronaviridae family. This disease was first identified in December 2019 in Wuhan, China; however, it has caused a global pandemic. This study was aimed to investigate the basic reproduction number (R0), epidemiological and clinical characteristics of COVID-19 patients in Jiroft, Kerman, Iran. Materials & Methods: This prospective, cross-sectional study was conducted during March-August 2020 on COVID-19 patients (positive RT-PCR) of the Jiroft population. Patients were followed for their epidemiological and clinical outcomes. The basic reproduction number was calculated, and the serial interval was modeled as a gamma distribution. Findings: Among 6550 highly suspicious patients, 3003 were positive for COVID-19. There were significant differences in clinical characteristics between outpatients and inpatients individuals. Early in the epidemic, the Rt was >2, which decreased to <1 until 19 April, when many interventions were implemented in Iran. The Rt increased to >1 from April until mid-June, but it reduced to <1 in July, and the epidemic was controlled. Conclusion: We estimated that R0 at the beginning of the epidemic in March 2020 was more than two, which reached to under one in July 2020. Identifying the clinical and epidemiological aspects of COVID-19 helps manage this disease in Iran and other parts of the world.