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Clinical characteristics of 24 asymptomatic infections with COVID-19 screened among close contacts in Nanjing, China.
Sci China Life Sci. 2020 05; 63(5):706-711.SC

Abstract

Previous studies have showed clinical characteristics of patients with the 2019 novel coronavirus disease (COVID-19) and the evidence of person-to-person transmission. Limited data are available for asymptomatic infections. This study aims to present the clinical characteristics of 24 cases with asymptomatic infection screened from close contacts and to show the transmission potential of asymptomatic COVID-19 virus carriers. Epidemiological investigations were conducted among all close contacts of COVID-19 patients (or suspected patients) in Nanjing, Jiangsu Province, China, from Jan 28 to Feb 9, 2020, both in clinic and in community. Asymptomatic carriers were laboratory-confirmed positive for the COVID-19 virus by testing the nucleic acid of the pharyngeal swab samples. Their clinical records, laboratory assessments, and chest CT scans were reviewed. As a result, none of the 24 asymptomatic cases presented any obvious symptoms while nucleic acid screening. Five cases (20.8%) developed symptoms (fever, cough, fatigue, etc.) during hospitalization. Twelve (50.0%) cases showed typical CT images of ground-glass chest and 5 (20.8%) presented stripe shadowing in the lungs. The remaining 7 (29.2%) cases showed normal CT image and had no symptoms during hospitalization. These 7 cases were younger (median age: 14.0 years; P=0.012) than the rest. None of the 24 cases developed severe COVID-19 pneumonia or died. The median communicable period, defined as the interval from the first day of positive nucleic acid tests to the first day of continuous negative tests, was 9.5 days (up to 21 days among the 24 asymptomatic cases). Through epidemiological investigation, we observed a typical asymptomatic transmission to the cohabiting family members, which even caused severe COVID-19 pneumonia. Overall, the asymptomatic carriers identified from close contacts were prone to be mildly ill during hospitalization. However, the communicable period could be up to three weeks and the communicated patients could develop severe illness. These results highlighted the importance of close contact tracing and longitudinally surveillance via virus nucleic acid tests. Further isolation recommendation and continuous nucleic acid tests may also be recommended to the patients discharged.

Authors+Show Affiliations

Nanjing Infectious Disease Center, the Second Hospital of Nanjing, Nanjing University of Chinese Medicine, Nanjing, 210003, China. Department of Epidemiology, Center for Global Health, School of Public Health, Nanjing Medical University, Nanjing, 211166, China.Department of Epidemiology, Center for Global Health, School of Public Health, Nanjing Medical University, Nanjing, 211166, China. State Key Laboratory of Reproductive Medicine, Nanjing Medical University, Nanjing, 211166, China.Department of Radiology, the Second Hospital of Nanjing, Nanjing University of Chinese Medicine, Nanjing, 210003, China.Department of Epidemiology, Center for Global Health, School of Public Health, Nanjing Medical University, Nanjing, 211166, China. State Key Laboratory of Reproductive Medicine, Nanjing Medical University, Nanjing, 211166, China.Nanjing Infectious Disease Center, the Second Hospital of Nanjing, Nanjing University of Chinese Medicine, Nanjing, 210003, China.Department of Epidemiology, Center for Global Health, School of Public Health, Nanjing Medical University, Nanjing, 211166, China.Department of Epidemiology, Center for Global Health, School of Public Health, Nanjing Medical University, Nanjing, 211166, China. State Key Laboratory of Reproductive Medicine, Nanjing Medical University, Nanjing, 211166, China.Department of Clinical Research Center, the Second Hospital of Nanjing, Nanjing University of Chinese Medicine, Nanjing, 210003, China.Department of Maternal, Child and Adolescent Health, School of Public Health, Nanjing Medical University, Nanjing, 211166, China.Department of Critical Medicine, the Second Hospital of Nanjing, Nanjing University of Chinese Medicine, Nanjing, 210003, China.Department of Epidemiology, Center for Global Health, School of Public Health, Nanjing Medical University, Nanjing, 211166, China.Nanjing Infectious Disease Center, the Second Hospital of Nanjing, Nanjing University of Chinese Medicine, Nanjing, 210003, China. zhibin_hu@njmu.edu.cn.Nanjing Infectious Disease Center, the Second Hospital of Nanjing, Nanjing University of Chinese Medicine, Nanjing, 210003, China. ian0126@126.com.Department of Epidemiology, Center for Global Health, School of Public Health, Nanjing Medical University, Nanjing, 211166, China. State Key Laboratory of Reproductive Medicine, Nanjing Medical University, Nanjing, 211166, China.

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

32146694

Citation

Hu, Zhiliang, et al. "Clinical Characteristics of 24 Asymptomatic Infections With COVID-19 Screened Among Close Contacts in Nanjing, China." Science China. Life Sciences, vol. 63, no. 5, 2020, pp. 706-711.
Hu Z, Song C, Xu C, et al. Clinical characteristics of 24 asymptomatic infections with COVID-19 screened among close contacts in Nanjing, China. Sci China Life Sci. 2020;63(5):706-711.
Hu, Z., Song, C., Xu, C., Jin, G., Chen, Y., Xu, X., Ma, H., Chen, W., Lin, Y., Zheng, Y., Wang, J., Hu, Z., Yi, Y., & Shen, H. (2020). Clinical characteristics of 24 asymptomatic infections with COVID-19 screened among close contacts in Nanjing, China. Science China. Life Sciences, 63(5), 706-711. https://doi.org/10.1007/s11427-020-1661-4
Hu Z, et al. Clinical Characteristics of 24 Asymptomatic Infections With COVID-19 Screened Among Close Contacts in Nanjing, China. Sci China Life Sci. 2020;63(5):706-711. PubMed PMID: 32146694.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Clinical characteristics of 24 asymptomatic infections with COVID-19 screened among close contacts in Nanjing, China. AU - Hu,Zhiliang, AU - Song,Ci, AU - Xu,Chuanjun, AU - Jin,Guangfu, AU - Chen,Yaling, AU - Xu,Xin, AU - Ma,Hongxia, AU - Chen,Wei, AU - Lin,Yuan, AU - Zheng,Yishan, AU - Wang,Jianming, AU - Hu,Zhibin, AU - Yi,Yongxiang, AU - Shen,Hongbing, Y1 - 2020/03/04/ PY - 2020/02/27/received PY - 2020/03/03/accepted PY - 2020/3/9/pubmed PY - 2020/4/28/medline PY - 2020/3/9/entrez KW - COVID-19 KW - China KW - asymptomatic infections KW - close contact SP - 706 EP - 711 JF - Science China. Life sciences JO - Sci China Life Sci VL - 63 IS - 5 N2 - Previous studies have showed clinical characteristics of patients with the 2019 novel coronavirus disease (COVID-19) and the evidence of person-to-person transmission. Limited data are available for asymptomatic infections. This study aims to present the clinical characteristics of 24 cases with asymptomatic infection screened from close contacts and to show the transmission potential of asymptomatic COVID-19 virus carriers. Epidemiological investigations were conducted among all close contacts of COVID-19 patients (or suspected patients) in Nanjing, Jiangsu Province, China, from Jan 28 to Feb 9, 2020, both in clinic and in community. Asymptomatic carriers were laboratory-confirmed positive for the COVID-19 virus by testing the nucleic acid of the pharyngeal swab samples. Their clinical records, laboratory assessments, and chest CT scans were reviewed. As a result, none of the 24 asymptomatic cases presented any obvious symptoms while nucleic acid screening. Five cases (20.8%) developed symptoms (fever, cough, fatigue, etc.) during hospitalization. Twelve (50.0%) cases showed typical CT images of ground-glass chest and 5 (20.8%) presented stripe shadowing in the lungs. The remaining 7 (29.2%) cases showed normal CT image and had no symptoms during hospitalization. These 7 cases were younger (median age: 14.0 years; P=0.012) than the rest. None of the 24 cases developed severe COVID-19 pneumonia or died. The median communicable period, defined as the interval from the first day of positive nucleic acid tests to the first day of continuous negative tests, was 9.5 days (up to 21 days among the 24 asymptomatic cases). Through epidemiological investigation, we observed a typical asymptomatic transmission to the cohabiting family members, which even caused severe COVID-19 pneumonia. Overall, the asymptomatic carriers identified from close contacts were prone to be mildly ill during hospitalization. However, the communicable period could be up to three weeks and the communicated patients could develop severe illness. These results highlighted the importance of close contact tracing and longitudinally surveillance via virus nucleic acid tests. Further isolation recommendation and continuous nucleic acid tests may also be recommended to the patients discharged. SN - 1869-1889 UR - https://www.unboundmedicine.com/medline/citation/32146694/full_citation L2 - https://dx.doi.org/10.1007/s11427-020-1661-4 DB - PRIME DP - Unbound Medicine ER -