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What We Did
Using data on imported and domestic COVID-19 cases from Taiwan and New Zealand between January and June 2020, we develop an epidemic surveillance model to detect cluster infections from imported cases. Taiwan and New Zealand are among a few countries in the world with a small number of COVID-19 cases. Taiwan is a long term-oriented and collectivistic country with a large power distance; in contrast, New Zealand is an individualistic and short-term oriented country with a small power distance. Despite their markedly different cultures and their strong tourism connections with China, both countries have been successful in containing the outbreak of COVID-19. As we employ empirical data of these two countries, we find remarkable consistency in the predictive power of the model. An increase in one imported case increased the risk of domestic cases by 9.54% in Taiwan and 10.97% in New Zealand. The Taiwan epidemic curve revealed that imported cases did not lead to a large-scale community-acquired outbreak. In New Zealand, a community-acquired outbreak during 29th March-4th April could have been averted if control actions had been taken one-week earlier prior to the predicted cluster infection between 22nd and 28th March.
Who Was Involved
- Dr. Yen-Po Yeh, Changhua County Public Health Bureau, and College of Public Health, National Taiwan University, Taipei
- Dr. Hsiao-Hsuan Jen, College of Public Health, National Taiwan University, Taipei
- Prof. Chang-Chuan Chan, College of Public Health, National Taiwan University, Taipei
- Prof. C. Jason Wang, Stanford University School of Medicine, Stanford
- Prof. Michael C. Lu, School of Public Health, University of California, Berkeley
- Dr. Szu-Min Peng, College of Public Health, National Taiwan University, Taipei
- Dr. Chen-Yang Hsu, College of Public Health, National Taiwan University, Taipei
- Prof. Sam Li-Sheng Chen, College of Oral Medicine, Taipei Medical University, Taipei
- Prof. Amy Ming-Fang Yen, College of Oral Medicine, Taipei Medical University, Taipei
- Prof. Hsiu-Hsi Chen, College of Public Health, National Taiwan University, Taipei
This work was financially supported by the Ministry of Science and Technology (Grant No. MOST 107-3017-F-002-003, 108-2118-M-002-002-MY3,108-2118-M-038-001-MY3, 108-2118-M-038-002-MY3, 109-2327-B-002 -009) and the ‘Innovation and Policy Center for Population Health and Sustainable Environment, College of Public Health, National Taiwan University’ from The Featured Areas Research Center Program within the framework of the Higher Education Sprout Project by the Ministry of Education in Taiwan (NTU-107L9003).
Why It Matters
Understanding the impact of imported COVID-19 cases on the subsequent cluster infections is important for establishing travel bubbles or travel corridors. For both Taiwan and New Zealand, the key factor responsible for reducing the spread of COVID-19 is the strong actions taken at decisive time points during COVID-19 pandemic; e.g., banning travelers who are neither residents nor citizens to enter each country.
Our model can be used as an early warning of outbreaks during the initial stage of pandemic or the resurgence of outbreaks after lifting containment measures, such as lockdown orders and border control. Such a quantitative surveillance model would be useful for monitoring, alerting and preventing large-scale community-acquired outbreaks during border reopening for selected countries with COVID-19 under control.
