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Infectivity of Coronavirus Disease 2019: A Prospective Cohort Study in the Korean Metropolitan Area
Hyeri Seok1, Seungkwan Lim2, Ji-Yeon Kim3
1Division of Infectious Diseases, Department of Internal Medicine, Korea University Ansan Hospital, Korea University College of Medicine, Ansan, Korea.
Insights
This study analyzed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infectivity in South Korea. Higher secondary attack rates were observed in religious gatherings, workplaces, and schools compared to healthcare settings, with specific symptoms indicating increased infectivity.
Area of Science:
- Infectious Diseases
- Epidemiology
- Public Health
Background:
- Limited data exists on the infectivity of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus responsible for coronavirus disease 2019 (COVID-19).
- Understanding SARS-CoV-2 transmission dynamics is crucial for effective pandemic control.
Purpose of the Study:
- To analyze the infectivity of SARS-CoV-2.
- To identify factors associated with higher SARS-CoV-2 infectivity.
- To inform infection control strategies for COVID-19.
Main Methods:
- Prospective cohort study of COVID-19 patients in Gyeonggi-do, South Korea (January-April 2020).
- Real-time polymerase chain reaction (PCR) confirmed COVID-19 cases.
- Analysis of secondary attack rate (SAR) across different exposure settings and patient characteristics.
Main Results:
- The overall secondary attack rate (SAR) was 3.5%.
- SAR was significantly higher in religious gatherings (13.5%), workplaces (8.49%), and schools (6.38%) compared to healthcare facilities (1.92%).
- Sore throat, dyspnea, lower cycle threshold values, leukocytosis, and elevated bilirubin levels were associated with increased infectivity; symptom presence was not a determining factor.
Conclusions:
- Variables associated with high infectivity, such as specific symptoms and exposure settings, should be considered when developing infection control strategies for COVID-19.
- Findings highlight the importance of targeted interventions in high-transmission environments.
Background:
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.
Methods:
This prospective cohort study was conducted to analyze the infectivity of SARS-CoV-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.
Results:
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.
Conclusion:
In establishing the infection control strategies for COVID-19, the variables associated with high infectivity may be considered.
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