J Korean Med Sci.  2022 Apr;37(14):e106. 10.3346/jkms.2022.37.e106.

Infectivity of Coronavirus Disease 2019: A Prospective Cohort Study in the Korean Metropolitan Area

  • 1Division of Infectious Diseases, Department of Internal Medicine, Korea University Ansan Hospital, Korea University College of Medicine, Ansan, Korea
  • 2Department of Internal Medicine, Gyeonggi Provincial Medical Center, Ansung Hospital, Anseong, Korea
  • 3Division of Infectious Disease, Department of Medicine, Seongnam Citizens Medical Center, Seongnam, Korea
  • 4Department of Internal Medicine, Gyeonggi Provincial Medical Center, Icheon Hospital, Icheon, Korea
  • 5Department of Surgery, Gyeonggi Provincial Medical Center, Uijeongbu Hospital, Uijeongbu, Korea
  • 6Department of Internal Medicine, Gyeonggi Provincial Medical Center, Uijeongbu Hospital, Uijeongbu, Korea
  • 7Department of Internal Medicine, Gyeonggi Provincial Medical Center, Pocheon Hospital, Pocheon, Korea
  • 8Division of Infectious Disease, Department of Internal Medicine, Myongji Hospital, Goyang, Korea
  • 9Department of Internal Medicine, Armed Forces Capital Hospital, Seongnam, Korea
  • 10Department of Internal Medicine, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, Korea
  • 11Department of Pulmonary and Critical Care Medicine, Ajou University School of Medicine, Suwon, Korea
  • 12Department of Internal Medicine, Soonchunhyang University Bucheon Hospital, Bucheon, Korea
  • 13Infectious Disease Control Center, Gyeonggi Provincial Government, Suwon, Korea


Although several characteristics of coronavirus disease 2019 (COVID-19), an ongoing pandemic disease, have been identified, data on the infectivity of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are limited.
This prospective cohort study was conducted to analyze the infectivity of SARSCoV-2 based on data of all patients diagnosed with COVID-19 confirmed using real-time polymerase chain reaction test from January to April 2020 in Gyeonggi-do, the largest province in Korea.
Of the 502 patients, 298 consisting of 106 clusters with 5,909 contacts were included. Of these, 277 (93.0%) were symptomatic, and the most common symptoms were cough, fever, sputum, sore throat, and headache. A total of 94 patients (31.5%) had pneumonia, while 8 (2.7%) died during the follow-up period. The secondary attack rate (SAR) in the study population was 3.5% (204/5,909). In exposure settings, the SAR was higher in religious gathering (13.5% [95% confidence interval, 10.7–16.8%]), workplaces (8.49% [95% CI, 6.08–11.74%]), and schools (6.38% [95% CI, 3.39–11.69%]) than in health care facilities (1.92% [95% CI, 1.45–2.55%]). Sore throat at any period, dyspnea at diagnosis or any period, lower cycle threshold value in the lower respiratory tract samples, leukocytosis, and higher bilirubin levels were associated with higher infectivity of COVID-19. The presence of symptoms was not related to the infectivity.
In establishing the infection control strategies for COVID-19, the variables associated with high infectivity may be considered.


COVID-19; SARS-CoV-2; Transmission; Infection Control

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Young Hee Jung, Eun-Hye Ha, Kang Won Choe, Seungbok Lee, Dong Ho Jo, Wang Jun Lee
J Korean Med Sci. 2022;37(27):e213.    doi: 10.3346/jkms.2022.37.e213.


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