Coronavirus (COVID-19) Collection
Quantifying the improvement in confirmation efficiency of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) during the early phase of the outbreak in Hong Kong in 2020The deadly coronavirus disease (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2, formerly 2019-nCoV), has emerged in Wuhan, China, in December 2019 (WHO, 2020). COVID-19 cases were soon exported to other Chinese cities and overseas, mainly owing to the traffic surge near the Chinese Lunar New Year (Bogoch et al., 2020; Wu et al., 2020). The first imported cases in Hong Kong were confirmed and reported on January 23, 2020, see Fig. 1(a). Since then, the government of Hong Kong has implemented a series of control and prevention measures for COVID-19, including enhanced border screening and traffic restrictions (summary, in press; CHP, in press).
The relative transmissibility of asymptomatic COVID-19 infections among close contactsNishiura et al. (2020) estimated the asymptomatic ratio of COVID-19 was 41.6% (5 out of 12 confirmed cases) among 565 Japanese individuals evacuated from Wuhan, China. Mao et al. (2020) reported that 2 out of 78 confirmed cases are asymptomatic. One of the two cases showed RT-PCT positivity 15th days after first diagnosis. Mizumoto et al. (2020) estimated that the 17.9% of cases on the Diamond Princess Cruise Ship were asymptomatic case during the outbreak in February 2020. However, the transmissibility of asymptomatic case is unclear, and the positive RT-PCT results only imply the potential infectivity.