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Comparison of Estimated Effectiveness of Case-Based and Population-Based Interventions on COVID-19 Containment in Taiwan

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To identify the key insights or developments described in this article
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Key Points

Question  What are the explanations for the initial success of COVID-19 control in Taiwan, a country that has one of the lowest per capita incidence and mortality rates in the world?

Findings  In this comparative effectiveness research study that used detailed epidemiologic and contact tracing data, neither case-based interventions (including contact tracing and quarantine) or population-based interventions (including social distancing and facial masking) alone were estimated to have been sufficient to contain COVID-19. The combination of case-based and population-based interventions was needed.

Meaning  The combination of case-based interventions with population-based interventions with wide adherence may explain the success of COVID-19 control in Taiwan.


Importance  Taiwan is one of the few countries with initial success in COVID-19 control without strict lockdown or school closure. The reasons remain to be fully elucidated.

Objective  To compare and evaluate the effectiveness of case-based (including contact tracing and quarantine) and population-based (including social distancing and facial masking) interventions for COVID-19 in Taiwan.

Design, Setting, and Participants  This comparative effectiveness study used a stochastic branching process model using COVID-19 epidemic datafrom Taiwan, an island nation of 23.6 million people, with no locally acquired cases of COVID-19 reported for 253 days between April and December 2020.

Main Outcomes and Measures  Effective reproduction number of COVID-19 cases (the number of secondary cases generated by 1 primary case) and the probability of outbreak extinction (0 new cases within 20 generations). For model development and calibration, an estimation of the incubation period (interval from exposure to symptom onset), serial interval (time between symptom onset in an infector-infectee pair), and the statistical distribution of the number of any subsequent infections generated by 1 primary case was calculated.

Results  This study analyzed data from 158 confirmed COVID-19 cases (median age, 45 years; interquartile range, 25-55 years; 84 men [53%]). An estimated 55% (95% credible interval [CrI], 41%-68%) of transmission events occurred during the presymptomatic stage. In our estimated analysis, case detection, contact tracing, and 14-day quarantine of close contacts (regardless of symptoms) was estimated to decrease the reproduction number from the counterfactual value of 2.50 to 1.53 (95% CrI, 1.50-1.57), which would not be sufficient for epidemic control, which requires a value of less than 1. In our estimated analysis, voluntary population-based interventions, if used alone, were estimated to have reduced the reproduction number to 1.30 (95% CrI, 1.03-1.58). Combined case-based and population-based interventions were estimated to reduce the reproduction number to below unity (0.85; 95% CrI, 0.78-0.89). Results were similar for additional analyses with influenza data and sensitivity analyses.

Conclusions and Relevance  In this comparative effectiveness research study, the combination of case-based and population-based interventions (with wide adherence) may explain the success of COVID-19 control in Taiwan in 2020. Either category of interventions alone would have been insufficient, even in a country with an effective public health system and comprehensive contact tracing program. Mitigating the COVID-19 pandemic requires the collaborative effort of public health professionals and the general public.

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Article Information

Accepted for Publication: March 12, 2021.

Published Online: April 6, 2021. doi:10.1001/jamainternmed.2021.1644

Corresponding Author: Hsien-Ho Lin, MD, ScD, Institute of Epidemiology and Preventive Medicine, College of Public Health, National Taiwan University, 17 Xuzhou Rd, Rm 706, Taipei 10055, Taiwan (

Open Access: This is an open access article distributed under the terms of the CC-BY License. © 2021 Ng T-C et al. JAMA Internal Medicine.

Author Contributions: Mr Ng and Dr Cheng contributed equally. Dr Lin had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.

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

Acquisition, analysis, or interpretation of data: Ng, Cheng, Chang, C. Liu, Yang, D. Liu, Cohen, Lin.

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

Critical revision of the manuscript for important intellectual content: Ng, Cheng, Chang, C. Liu, Yang, D. Liu, Cohen, Lin.

Statistical analysis: Ng, Cheng, Chang, C. Liu, Yang, Jian.

Obtained funding: Lin.

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

Supervision: D. Liu, Lin.

Conflict of Interest Disclosures: Dr Cohen reported grants from the National Institutes of Health outside the submitted work. No other disclosures were reported.

Funding/Support: This research was supported by Taiwan Ministry of Science and Technology (MOST 109-2327-B-002-009).

Role of the Funder/Sponsor: The funding organization 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.

Additional Contributions: We thank Hung Hung, PhD, National Taiwan University, for the statistical consultation without compensation.

Data Sharing Statement: The data sets generated and analyzed during the current study are available from the corresponding author on request. Codes are available on GitHub at

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