Taiwan has received unanimous applause for its handling of the pandemic, with one of the lowest per capita covid-19 rates in the world and a situation that is largely tending to normal.
Only 11 people have died from covid-19 in Taiwan since the start of the pandemic, an impressive feat for a country that was never confined.
At the beginning of the pandemic, Taiwan was considered a high-risk country for COVID-19 due to its proximity to China and the frequent travel between the two countries.
With a SARS record in 2003 that was not particularly well managed, this time the Taiwanese government acted quickly to close its borders. On January 20, 2020, it created a Central Command for Epidemics to coordinate cooperation between the different ministries and government agencies, and between the government and companies.
A new study has further examined why Taiwan has done so well in the fight against COVID-19. The study authors, drawn from various health institutes and hospitals in Taiwan and the United States, compared the estimated efficacy of two types of policies in the early months of the pandemic: case-based measures and population-based measures.
Case-based measures include detection of infected people through testing, isolation of positive cases, contact tracing, and 14-day quarantine of close contacts.
Population-based measures included mask wear, personal hygiene, and social distancing.
The effects of these measures were quantified by estimating the effective reproduction number (R number).
The R number is a way of rating the ability to spread an infectious disease: it represents the average number of people to whom an infected person will transmit the infection. An R number greater than 1 means that the virus will continue to spread and outbreaks will continue. An R number less than 1 means that the number of cases will start to decrease.
While previous studies in other countries have simulated what-if scenarios, this work combined transmission modeling with detailed actual data to estimate efficacy.
The authors collected data on 158 cases between January 10 and June 1, 2020 from the Taiwan Centers for Disease Control. All cases were confirmed by PCR tests. The data referred to local infections, confirmed groups, and imported cases of people who entered Taiwan before March 21, 2020.
They then compared the results they found in Taiwan with an R of 2.5, based on the estimated equivalent number in neighboring China at the start of their covid-19 outbreak.
The winning combination
The study found that case-based policies alone, such as contact tracing and quarantine, could reduce the R-number from 2.5 to 1.53. Confinement was the one that contributed the most to reducing the R number.
The case-based interventions could not substantially prevent person-to-person transmission, but they did succeed in reducing subsequent transmission to a third or fourth person, provided those close contacts were quarantined.
Population-based measures, such as social distancing and masks, reduced the R number from 2.5 to 1.3.
The authors concluded that it was the combination of case-based and population-based measures that led to Taiwan’s success in containing COVID. The combination of both approaches led to an R number, estimated by two different methods, of 0.82 and even 0.62. They also found that robust population-based measures were needed to achieve containment, even though the number of circulating infections was small.
Neither approach would have been sufficient on its own, even in a country with an effective public health system and a sophisticated contact tracing system.
How does this affect other countries?
Recognizing that all models make assumptions, and this analysis is no different, this paper confirms that the entire set of public health measures that we have been using fairly consistently around the world – to varying degrees of temporality and rigor – have been necessary. Although it should be noted that the results of the study reflect a period in which the new variants with higher transmissibility were not a problem.
The authors assumed that testing and isolation occurred simultaneously. This was the case in Taiwan, but not in other countries such as England, where delays between tests, results, and confinement diminish the effectiveness of case-based measures.
Taiwan is an island nation with the ability to control the introduction of new cases through border control, and the authors acknowledge that the findings of this study may not be fully applicable to other countries. This is why the authors focused on the efficacy of population-based and case-based interventions on local transmission, and not on border controls on the number of imported COVID-19 cases.
The authors concluded that intensive contact tracing is not possible when public health systems are overwhelmed. This never happened in Taiwan due to the success of its strategies, but it did take place, for example, in Ireland in January 2021, when it experienced a harmful third wave of covid-19.
This paper also found similar results for the seven- and 14-day quarantine and suggests that the period of confinement could be shortened. Some countries are considering this possibility, including the United States, but to date it has not been widely introduced.
We already knew that there was much to learn from Taiwan’s success in preventing the epidemic from taking hold. Now, as vaccines are deployed and new variants emerge, we have more information about the comparative and combined contributions of public health measures.
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