COVID-19: How HK managed the first wave without a complete lockdown
Public health interventions and population behavioural changes have helped Hong Kong reduce the transmission of coronavirus disease 2019 (COVID-19) without resorting to a complete lockdown, and are also likely to have led to a substantial reduction in influenza transmission in early February 2020, an observational study by the University of Hong Kong (HKU) has shown.
As of 21st April 2020, 1,026 cases of COVID-19 were confirmed in Hong Kong. [https://chp-dashboard.geodata.gov.hk/covid-19/en.html] In the study, the researchers analyzed data on the 715 cases confirmed in Hong Kong as of 31st March 2020, including 386 imported cases, 142 unlinked local cases and 187 secondary cases. Among these cases, 94 were asymptomatic. A combination of intensive surveillance, border entry restrictions, quarantine, isolation of cases and contacts, and population behavioural changes, such as social distancing with flexible work arrangements, school closures and cancellation of large-scale events, had been implemented since late January to control local transmission of COVID-19. [Lancet 2020, doi: 10.1016/S0140-6736(20)30746-7]
While the number of unlinked cases had increased since early March likely due to imported cases, the transmissibility of COVID-19, as measured by the daily effective reproduction number (Rt), had remained around the critical threshold of 1 since early February, indicating a steady state of the epidemic in Hong Kong.
A concomitant rapid decline in the transmissibility of influenza in Hong Kong was observed following the implementation of social distancing measures. The estimated average Rt, based on outpatient surveillance data from the Centre for Health Protection, decreased from 1.28 in the 2 weeks prior to the start of school closures to 0.72 during the first 2 weeks of closures, corresponding to a 44 percent reduction (95 percent confidence interval [Cl], 34 to 53) in influenza transmissibility in the community in early February. A concurrent 33 percent reduction (95 percent CI, 24 to 43) was seen in daily paediatric hospitalization rates for influenza-positive cases, with a reduction of Rt from 1.10 to 0.73, based on data from two large hospitals in Hong Kong.
Results of three consecutive telephone surveys conducted from January to March 2020 among 3,013 adults in Hong Kong revealed changes in attitudes towards COVID-19 as well as population behaviours.
A majority (76.4 percent) of the respondents agreed with complete border closure to prevent the spread of COVID-19, whilst a greater proportion (84.1 percent) expressed concern on the availability of medical supplies, such as face masks.
Face masks were increasingly worn by the respondents when going out (from 74.5 percent in January to 97.5 percent and 98.8 percent in February and March, respectively). Hand washing or sanitization (61.3 percent, 90.2 percent and 85.1 percent, respectively) and avoidance of crowded places (71.1 percent, 92.5 percent and 93.0 percent, respectively) were also increasingly adopted by the respondents. Among respondents who were parents, 95.4 percent agreed with school closures as a measure to control COVID-19.
“By quickly implementing public health measures, Hong Kong has demonstrated that COVID-19 transmission can be effectively contained without resorting to the highly disruptive complete lockdown adopted by China, the US, and Western European countries,” said co-first author, Professor Benjamin Cowling of the School of Public Health, HKU. “Other governments can learn from the success of Hong Kong. If these measures and population responses can be sustained, while avoiding fatigue among the general population, they could substantially lessen the impact of a local COVID-19 epidemic.”