How Did Hong Kong Get Through COVID-19 Without a Complete Lockdown?

Hong Kong seems to have avoided a major outbreak of the novel coronavirus, at least through the end of March, according to a paper published in The Lancet Public Health. So, how did they accomplish this feat?

Investigators from Hong Kong examined the effects of their country’s public health measures that were designed to suppress local transmission of coronavirus disease 2019 (COVID-19). Their aim was to share the COVID-19 transmission dynamics as an effect of these interventions and behavioral changes from the public. Some of these measures included surveillance for infections in both incoming travelers and the locals, isolating COVID-19-positive cases, contact tracing and isolating those who have suspected cases, and social distancing.

The study authors assumed that influenza and COVID-19 spread similarly, so they used flu data to track potential changes in transmission among those who had been practicing Hong Kong’s public health measures. They collected data about influenza-like illness (fever and sore throat) from about 60 general outpatient clinics, as well as age and sex of patients. Their 3 study periods included January 20-23, February 11-14, and March 10-13.

The investigators included 1008 participants in the study for the January period, 1000 in the February period, and 1005 in the March period. Participants were called using a randomly generated phone number by computer system and were surveyed about their thoughts on measures of risk perception, attitudes towards COVID-19, behaviors taken against contracting the virus (hygiene, face masks, social distancing).

In a second and third survey, participants consisted of parents of school-aged children who were also asked about their children’s social patterns, as schools were closed during the study periods.

As of the end of March, Hong Kong had 715 confirmed COVID-19 cases, including 386 imported cases, 142 cases that could not be linked to any other case, and 187 cases linked to other known cases. Of the total number, 94 cases were asymptomatic, the investigators reported.

Transmissibility remained around 1, the investigators said. They attributed the risk in transmission of infections to increasing numbers of imported cases in early March.

Comparably, influenza activity peaked in the third week of January and transmissibility remained around 1, the study authors said. Transmissibility was greater than 1 before Chinese New Year, they added, which was significant as during the 2010-11 winter transmissibility for the flu was estimated to be at 15% around Chinese New Year. In the winter of 2014-15, transmissibility of the flu was 14%.

“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 USA, and Western European countries,” Benjamin Cowling, PhD, professor at the University of Hong Kong, said in a press release.

“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.”

Based on the phone calls, the investigators learned that 85% of those surveyed reported avoiding crowded places while almost all (99%) reported wearing face masks when leaving home by the third survey period. During the SARS outbreak in 2003, the study authors added, reported face mask use was around 79% in similar surveys and only about 10% during the H1N1 flu outbreak of 2009.

Three-quarters of those surveyed in February thought complete border closure would be effective in preventing the spread of COVID-19 to Hong Kong. Additionally, the study authors reported that 84% of those surveyed were worried about the availability of medical supplies like face masks, but only about a quarter were worried about availability of food and household goods.

Almost all of those surveyed who were parents agreed or strongly agreed that school closures were necessary as a measure of controlling COVID-19, the study authors noted.

“As both influenza and COVID-19 are directly transmissible respiratory pathogens with similar viral shedding dynamics, it’s likely that these control measures have also reduced COVID-19 transmission in the community,” study co-author Peng Wu, PhD, BMed , of the University of Hong Kong, added in the statement.

“As one of the most heavily affected epicenters during the SARS epidemic in 2003, Hong Kong is better equipped to contend with an outbreak of COVID-19 than many other countries. Improved testing and hospital capacity to handle novel respiratory pathogens, and a population acutely aware of the need to improve personal hygiene and maintain physical distancing, put them in good stead.”