Based on the new study by Harvard University, the approach adopted by Singapore in response to the Covid-19 outbreak is the “gold standard” for case detection. The researchers also used Singapore as a benchmark comparison for other nations.
If every other country had Singapore’s detection capacity, the number of global cases detected would have been 2.8 times more than the current figure, the study suggested.
“We consider the detection of 18 cases by Feb 4, 2020 in Singapore to be a gold standard of near-perfect detection… We estimated that detection of exported cases from Wuhan worldwide is 38 per cent as sensitive as it has been in Singapore,” the four epidemiologists at Harvard’s T. H. Chan School of Public Health remarked.
In what is called the “high surveillance” countries in the study, the number was 40 per cent whereas the detection capacity of “low surveillance” countries was merely 11 per cent of Singapore’s capacity.
The Global Health Security Index (GHSI) is an index that ranks countries based on their reporting and response capabilities and disease prevention detection in addition to other capacities. According to the study, high surveillance countries achieved the highest GHSI score.
The researchers in their previous study also pointed out how Singapore is a statistical anomaly with regards to their estimation of the number of cases in each country should have in relation to the travel volume from China.
Aggregated data from the World Health Organisation (WHO) report released on 4 Feb had been examined by the researchers. The WHO data contained the number of cases imported by tourists with known travel history to China to 191 regions and countries. However, Taiwan, Hong Kong and Macau were not included in the study.
Utilising historical data from the International Air Travel Association alongside other sources, the researchers estimated the number of air travel passengers per day from the origin of the virus, Wuhan, to places outside of China.
The authors reported that “among countries with substantial travel volume, Singapore showed the highest ratio of detected imported cases to daily travel volume, a ratio of one case per five daily travellers… Singapore is historically known for exceptionally sensitive detection of cases, for example in Sars (severe acute respiratory syndrome), and has had extremely detailed case reporting during the Covid-19 outbreak”.
This newest study suggests one implication that is, the virus could have been exported from Wuhan before the city was locked down, to various places across the world without being detected.
On Friday (14 Feb), the Harvard study was uploaded as an unpublished manuscript to medRxiv, a free online health sciences archive. Although the report is complete, the website notes that such manuscripts are “preliminary reports of work that have not been peer reviewed” that should not be relied on to guide clinical practice or health-related behaviour.