The Epidemiology of COVID-19 cases and the Successful Containment Strategy in Hong Kong – January to May 2020

Lam, Ho Yeung; Lam, Tsz Sum; Wong, Chi Hong; Lam, Wing Hang; Leung, Chi Mei Emily; Au, Ka Wing Albert; Lam, Chau Kuen Yonnie; Lau, Tin Wai Winnie; Chan, Yung Wai Desmond; Wong, Ka Hing; Chuang, Shuk Kwan

BACKGROUND: Hong Kong, a Special Administrative Region of China, recorded its first confirmed Coronavirus disease 2019 (COVID-19) case on 23 January 2020. We reviewed the case epidemiology and the various public health measures implemented from January to May 2020. METHOD: We described and compared the epidemiological and clinical characteristics of the cases recorded in different phases of the epidemic and reviewed the effectiveness of the public health measures implemented using the changes in the daily number of confirmed cases and the interval from symptom onset to hospital admission. RESULTS: Between January and May 2020, 1084 confirmed COVID-19 cases were reported, about 70% of which had travel history during the incubation period. The case fatality ratio was 0.4%. The local epidemic progressed through four phases: (i) preparedness and imported infection from mainland China, (ii) local transmission, (iii) imported infection from overseas countries associated with local transmission, and (iv) controlled imported infection with limited local transmission, with an eventual reduction of daily case number and minimization of onset-to-admission interval. Various public health measures, including enhanced surveillance, border control and social distancing, were introduced in phases in response to the prevailing local and global situations. DISCUSSION: Hong Kong’s overall containment strategy has led to a stabilization of number of cases and absence of community-wide outbreak in the 4.5 months since the reporting of the first case. Hong Kong’s strategy of containment might serve as an example for future planning of preparedness and response against novel infectious agents.