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Coronavirus (COVID-19)

Contact Tracing Assessment of COVID-19 Transmission Dynamics in Taiwan and Risk at Different Exposure Periods Before and After Symptom Onset

Educational Objective
To understand the transmissibility of COVID-19 between people in close contact with each other

1 Credit CME

JAMA Internal Medicine

Published Online: May 1, 2020

Original Investigation

Article Information and Disclosures

Hao-Yuan Cheng, MD, MSc¹;

Shu-Wan Jian, DVM, MPH¹;

Hsien-Ho Lin, MD, ScD^2,4;

for the Taiwan COVID-19 Outbreak Investigation Team

Author Affiliations

¹Epidemic Intelligence Center, Taiwan Centers for Disease Control, Taipei, Taiwan
²Institute of Epidemiology and Preventive Medicine, National Taiwan University College of Public Health, Taipei, Taiwan
³Office of Preventive Medicine, Taiwan Centers for Disease Control, Taipei, Taiwan
⁴Global Health Program, National Taiwan University College of Public Health, Taipei, Taiwan

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Key Points

Question What is the transmissibility of coronavirus disease 2019 (COVID-19) to close contacts?

Findings In this case-ascertained study of 100 cases of confirmed COVID-19 and 2761 close contacts, the overall secondary clinical attack rate was 0.7%. The attack rate was higher among contacts whose exposure to the index case started within 5 days of symptom onset than those who were exposed later.

Meaning High transmissibility of COVID-19 before and immediately after symptom onset suggests that finding and isolating symptomatic patients alone may not suffice to interrupt transmission, and that more generalized measures might be required, such as social distancing.

Abstract

Importance The dynamics of coronavirus disease 2019 (COVID-19) transmissibility are yet to be fully understood. Better understanding of the transmission dynamics is important for the development and evaluation of effective control policies.

Objective To delineate the transmission dynamics of COVID-19 and evaluate the transmission risk at different exposure window periods before and after symptom onset.

Design, Setting, and Participants This prospective case-ascertained study in Taiwan included laboratory-confirmed cases of COVID-19 and their contacts. The study period was from January 15 to March 18, 2020. All close contacts were quarantined at home for 14 days after their last exposure to the index case. During the quarantine period, any relevant symptoms (fever, cough, or other respiratory symptoms) of contacts triggered a COVID-19 test. The final follow-up date was April 2, 2020.

Main Outcomes and Measures Secondary clinical attack rate (considering symptomatic cases only) for different exposure time windows of the index cases and for different exposure settings (such as household, family, and health care).

Results We enrolled 100 confirmed patients, with a median age of 44 years (range, 11-88 years), including 44 men and 56 women. Among their 2761 close contacts, there were 22 paired index-secondary cases. The overall secondary clinical attack rate was 0.7% (95% CI, 0.4%-1.0%). The attack rate was higher among the 1818 contacts whose exposure to index cases started within 5 days of symptom onset (1.0% [95% CI, 0.6%-1.6%]) compared with those who were exposed later (0 cases from 852 contacts; 95% CI, 0%-0.4%). The 299 contacts with exclusive presymptomatic exposures were also at risk (attack rate, 0.7% [95% CI, 0.2%-2.4%]). The attack rate was higher among household (4.6% [95% CI, 2.3%-9.3%]) and nonhousehold (5.3% [95% CI, 2.1%-12.8%]) family contacts than that in health care or other settings. The attack rates were higher among those aged 40 to 59 years (1.1% [95% CI, 0.6%-2.1%]) and those aged 60 years and older (0.9% [95% CI, 0.3%-2.6%]).

Conclusions and Relevance In this study, high transmissibility of COVID-19 before and immediately after symptom onset suggests that finding and isolating symptomatic patients alone may not suffice to contain the epidemic, and more generalized measures may be required, such as social distancing.

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Article Information

Accepted for Publication: April 21, 2020.

Published Online: May 1, 2020. doi:10.1001/jamainternmed.2020.2020

Correction: This article was corrected on September 8, 2020, to fix transposed numbers of men and women study participants in the Abstract and in the Results section; an error in the definition of serial interval in the Introduction; the misspelling of 2 names in the Group Information section; and typographical data errors in the Supplement.

Corresponding Author: Hsien-Ho Lin, MD, ScD, National Taiwan University, 17 Xuzhou Rd, Taipei 100, Taiwan (hsienho@ntu.edu.tw).

Author Contributions: Drs Cheng and Lin had full access to all of the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis.

Concept and design: Cheng, Jian, Huang, Lin.

Acquisition, analysis, or interpretation of data: All authors.

Drafting of the manuscript: Cheng, Jian, Ng, Lin.

Critical revision of the manuscript for important intellectual content: Cheng, Jian, Liu, Huang, Lin.

Statistical analysis: Cheng, Jian, Ng, Lin.

Obtained funding: Lin.

Administrative, technical, or material support: Jian, Liu, Ng, Huang, Lin.

Supervision: Liu, Huang, Lin.

Conflict of Interest Disclosures: None reported.

Funding/Support: The study was funded by Taiwan Ministry of Science and Technology (MOST 107-2314-B-002-187-MY2 and MOST 108-2628-B-002-022).

Role of the Funder/Sponsor: The funder had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.

Group Information: The Taiwan COVID-19 Outbreak Investigation Team members include the following: Taiwan CDC: Office of Preventive Medicine and Taiwan Field Epidemiology Training Program: Wan-Ting Huang, Wan-Chin Chen, Angela Song-En Huang, Chia-Ping Su, Pin-Hui Lee, Pei-Chun Chan, Hao-Hsin Wu, Shih-Tse Huang, Tsung-Pei Tsou, Ying-Shih Su, and Yang Li. Taipei Regional Control Center: Hsin-Yi Wei, Meng-Yu Chen, Shiao-Ping Tung, Yu-Fang Tsai, Xiang-Ting Huang, and Chien-Yu Chou. North Regional Control Center: Pei-Yuan Wu, Fang-Tzu Chang, Chia-Ying Yen, Hsueh-Mei Chiang, Ju-Hui Lin, and Ming-Chu Tai. Central Regional Control Center: Kung-Chin Wang, Ching-Fen Ko, Pei-Fang Lai, Du-Ling Lin, Min-Tsung Lin, and Zhi-Jie Ding. South Regional Control Center: Huai-Te Tsai, Ping-Jung Liu, Pei-Yi Lin, Shu-Chen Chang, and Yi-Ying Lin. Kao-Ping Regional Control Center: Hsin-Chun Lee, Chi-Nan Hung, Ching-Li Lin, Chi-Mei Lai, and Hsiao-Mei Liu.

Additional Contributions: We thank the Taiwan COVID-19 Outbreak Investigation Team, the staffs of regional control centers of the Taiwan Centers for Disease Control (CDC), and partners from other public health bureaus (Taipei City, New Taipei City, Taoyuan City, Taichung City, Tainan City, Kaohsiung City, Changhua, Nantou, Hsinchu, Miaoli, Yunlin, and Ilan County) for their dedicated outbreak investigation and meticulous date collection. Our study could not have been done without their efforts. We also thank Chia-Lin Lee, MSc, and Yu-Lun Liu, MD, MSc, for the development of electronic contact tracing system (Epidemic Intelligence Center, Taiwan CDC); Ching-Hung Wang (TonyQ) for the consultation of system development; Angela Song-En Huang, MD, MPH (Office of Preventive Medicine, Taiwan CDC), for writing assistance. They did not receive compensation outside of their salary.

References

Zhu N , Zhang D , Wang W , et al; China Novel Coronavirus Investigating and Research Team. A novel coronavirus from patients with pneumonia in China, 2019. N Engl J Med. 2020;382(8):727-733. doi:10.1056/NEJMoa2001017 PubMed Google Scholar

World Health Organization. Coronavirus disease 2019 (COVID-19) situation report—48. Published March 8, 2020. Accessed April 5, 2020. https://www.who.int/docs/default-source/coronaviruse/situation-reports/20200308-sitrep-48-covid-19.pdf?sfvrsn=16f7ccef_4

Lipsitch M , Swerdlow DL , Finelli L . Defining the epidemiology of Covid-19—studies needed. N Engl J Med. 2020;382(13):1194-1196. doi:10.1056/NEJMp2002125 PubMed Google Scholar

Nishiura H , Linton NM , Akhmetzhanov AR . Serial interval of novel coronavirus (COVID-19) infections. Int J Infect Dis. 2020;93:284-286. doi:10.1016/j.ijid.2020.02.060 PubMed Google Scholar

Zou L , Ruan F , Huang M , et al. SARS-CoV-2 viral load in upper respiratory specimens of infected patients. N Engl J Med. 2020;382(12):1177-1179. doi:10.1056/NEJMc2001737 PubMed Google Scholar

Pan Y , Zhang D , Yang P , Poon LLM , Wang Q . Viral load of SARS-CoV-2 in clinical samples. Lancet Infect Dis. 2020;20(4):411-412. doi:10.1016/S1473-3099(20)30113-4 PubMed Google Scholar

Liu J , Liao X , Qian S , et al. Community transmission of severe acute respiratory syndrome coronavirus 2, Shenzhen, China, 2020. Emerg Infect Dis. 2020;26(6):507. doi:10.3201/eid2606.200239 PubMed Google Scholar

Patel A , Jernigan DB , Abdirizak F , et al; 2019-nCoV CDC Response Team. Initial public health response and interim clinical guidance for the 2019 novel coronavirus outbreak—United States, December 31, 2019-February 4, 2020. MMWR Morb Mortal Wkly Rep. 2020;69(5):140-146. doi:10.15585/mmwr.mm6905e1 PubMed Google Scholar

World Health Organization. Report of the WHO-China joint mission on coronavirus disease 2019 (COVID-19). Published February 28, 2020. Accessed April 5, 2020. https://www.who.int/docs/default-source/coronaviruse/who-china-joint-mission-on-covid-19-final-report.pdf

10.

Cheng S-C , Chang Y-C , Fan Chiang YL , et al. First case of coronavirus disease 2019 (COVID-19) pneumonia in Taiwan. J Formos Med Assoc. 2020;119(3):747-751. doi:10.1016/j.jfma.2020.02.007 PubMed Google Scholar

11.

Cheng H-Y , Li S-Y , Yang C-H . Initial rapid and proactive response for the COVID-19 outbreak—Taiwan’s experience. J Formos Med Assoc. 2020;119(4):771-773. doi:10.1016/j.jfma.2020.03.007 PubMed Google Scholar

12.

Wang CJ , Ng CY , Brook RH . Response to COVID-19 in Taiwan. JAMA. 2020;323(14):1341-1342. doi:10.1001/jama.2020.3151 PubMed Google Scholar

13.

von Elm E , Altman DG , Egger M , Pocock SJ , Gøtzsche PC , Vandenbroucke JP ; STROBE Initiative. The Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) statement: guidelines for reporting observational studies. Lancet. 2007;370(9596):1453-1457. doi:10.1016/S0140-6736(07)61602-X PubMed Google Scholar

14.

Taiwan Legislative Yuan. The Communicable Disease Control Act. Accessed April 18, 2020. https://law.moj.gov.tw/ENG/LawClass/LawAll.aspx?pcode=L0050001

15.

Corman VM , Landt O , Kaiser M , et al. Detection of 2019 novel coronavirus (2019-nCoV) by real-time RT-PCR. Euro Surveill. 2020;25(3):2000045. doi:10.2807/1560-7917.ES.2020.25.3.2000045 PubMed Google Scholar

16.

Jian S-W , Chen C-M , Lee C-Y , Liu D-P . Real-time surveillance of infectious diseases: Taiwan’s experience. Health Secur. 2017;15(2):144-153. doi:10.1089/hs.2016.0107 PubMed Google Scholar

17.

World Health Organization. Clinical management of severe acute respiratory infection when COVID-19 is suspected. Published March 13, 2020. Accessed April 5, 2020. https://www.who.int/publications-detail/clinical-management-of-severe-acute-respiratory-infection-when-novel-coronavirus-(ncov)-infection-is-suspected

18.

Taiwan Centers for Disease Control. Infectious disease contact tracing platform and management system. Accessed April 18, 2020. https://www.cdc.gov.tw/Professional/ProgramResultInfo/LeYn5b0UwF_lgvjR5rhT-A?programResultId=I2JMxghoGbL10LOSBG3h5Q

19.

World Health Organization. The First Few X (FFX) Cases and contact investigation protocol for 2019-novel coronavirus (2019-nCoV) infection. Published January 29, 2020. Accessed April 5, 2020. https://www.who.int/publications-detail/the-first-few-x-(ffx)-cases-and-contact-investigation-protocol-for-2019-novel-coronavirus-(2019-ncov)-infection

20.

Lipsitch M , Cohen T , Cooper B , et al. Transmission dynamics and control of severe acute respiratory syndrome. Science. 2003;300(5627):1966-1970. doi:10.1126/science.1086616 PubMed Google Scholar

21.

Wölfel R , Corman VM , Guggemos W , et al. Virological assessment of hospitalized patients with COVID-2019. Nature. Published online April 1, 2020. doi:10.1038/s41586-020-2196-x PubMed Google Scholar

22.

Huang C , Wang Y , Li X , et al. Clinical features of patients infected with 2019 novel coronavirus in Wuhan, China. Lancet. 2020;395(10223):497-506. doi:10.1016/S0140-6736(20)30183-5 PubMed Google Scholar

23.

Wang D , Hu B , Hu C , et al. Clinical characteristics of 138 hospitalized patients with 2019 novel coronavirus-infected pneumonia in Wuhan, China. JAMA. 2020;323(11). doi:10.1001/jama.2020.1585 PubMed Google Scholar

24.

Hellewell J , Abbott S , Gimma A , et al; Centre for the Mathematical Modelling of Infectious Diseases COVID-19 Working Group. Feasibility of controlling COVID-19 outbreaks by isolation of cases and contacts. Lancet Glob Health. 2020;8(4):e488-e496. doi:10.1016/S2214-109X(20)30074-7 PubMed Google Scholar

25.

World Health Organization. Home care for patients with COVID-19 presenting with mild symptoms and management of their contacts. Published March 17, 2020. Assessed April 5, 2020. https://www.who.int/publications-detail/home-care-for-patients-with-suspected-novel-coronavirus-(ncov)-infection-presenting-with-mild-symptoms-and-management-of-contacts

26.

Wu Z , McGoogan JM . Characteristics of and important lessons from the coronavirus disease 2019 (COVID-19) outbreak in China: summary of a report of 72 314 cases from the Chinese Center for Disease Control and Prevention. JAMA. 2020;323(13). doi:10.1001/jama.2020.2648 PubMed Google Scholar

27.

Ji Y , Ma Z , Peppelenbosch MP , Pan Q . Potential association between COVID-19 mortality and health-care resource availability. Lancet Glob Health. 2020;8(4):e480. doi:10.1016/S2214-109X(20)30068-1 PubMed Google Scholar

28.

Li Q , Guan X , Wu P , et al. Early transmission dynamics in Wuhan, China, of novel coronavirus-infected pneumonia. N Engl J Med. 2020;382(13):1199-1207. doi:10.1056/NEJMoa2001316 PubMed Google Scholar

29.

Nishiura H . Backcalculating the incidence of infection with COVID-19 on the Diamond Princess. J Clin Med. 2020;9(3):657. doi:10.3390/jcm9030657 PubMed Google Scholar

30.

Ong SWX , Tan YK , Chia PY , et al. Air, surface environmental, and personal protective equipment contamination by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) from a symptomatic patient. JAMA. 2020;323(16). doi:10.1001/jama.2020.3227 PubMed Google Scholar

31.

Bin SY , Heo JY , Song M-S , et al. Environmental contamination and viral shedding in MERS patients during MERS-CoV outbreak in South Korea. Clin Infect Dis. 2016;62(6):755-760. doi:10.1093/cid/civ1020 PubMed Google Scholar

32.

Kim S-H , Chang SY , Sung M , et al. Extensive viable Middle East Respiratory Syndrome (MERS) coronavirus contamination in air and surrounding environment in MERS isolation wards. Clin Infect Dis. 2016;63(3):363-369. doi:10.1093/cid/ciw239 PubMed Google Scholar

33.

Google. COVID-19 community mobility reports. Accessed April 16, 2020. https://www.google.com/covid19/mobility/

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Credit Designation Statement: The American Medical Association designates this Journal-based CME activity activity for a maximum of 1.00  AMA PRA Category 1 Credit(s)™. Physicians should claim only the credit commensurate with the extent of their participation in the activity.

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