Inferring super-spreading from transmission clusters of COVID-19 in Hong Kong, Japan, and Singapore

Abstract

Super-spreading events in an outbreak can change the nature of an epidemic. Therefore, it is useful for public health teams to determine whether an ongoing outbreak has any contribution from such events, which may be amenable to interventions. We estimated the basic reproductive number (R 0 ) and the dispersion factor (k) from empirical data on clusters of epidemiologically linked coronavirus disease 2019 (COVID-19) cases in Hong Kong, Japan and Singapore. This allowed us to infer the presence or absence of superspreading events during the early phase of these outbreaks. The relatively large values of k implied that large cluster sizes, compatible with super-spreading, were unlikely.

Settings of virus exposure and their implications in the propagation of transmission networks in a COVID-19 outbreak

“…The pattern of superspreading events may however vary between outbreaks, and superspreaders could be unidentified or identified only after the event. An analysis of epidemiological data of 101 cases collected early in the epidemic as of 3 March 2020 in Hong Kong, Japan and Singapore suggested transmission was not overdispersed and did not find strong evidence for the presence of superspreading events [9] . However subsequent studies including one done in Hong Kong analysing 1,037 cases as of 28 April showed substantial individual heterogeneity in transmissibility ( k = 0·45, 95%; 0·3-0·72) [10] .…”

Successful Government Responses to the Pandemic

“…Such differences cannot be explained only by the policy designed by the government in power and the values on which it bases its decisions, when weighing between, let's say, human lives vs. economy, individual freedom vs. common good, or democracy vs. efficiency. There is a range of other factors to be taken into account, such as the initial conditions and early development of the outbreak of the disease as it unfolds, the global and regional connectedness of the country especially regarding the connections with the birthplace of the virus, COVID-19 epicenters or superspreading events (Frieden & Lee, 2020;Kwok et al, 2020), and the national and local cultures that affect the spread of the virus through customs, the patterns of social interaction and norm compliance. In addition, this is a rapidly changing phenomenon, which due to accidents or the behavior of a few individuals may provide surprises even to countries that have prepared well for these kinds of crises.…”

Superimposed threats to population health from tropical cyclones in the prevaccine era of COVID-19

“…This likelihood is underscored by evidence indicating that COVID-19 spreads readily via asymptomatic 8 and airborne transmission 9 and superspreader events. 10 Recent tropical cyclones that have made landfall on island-based populations and coastal populations illustrate the dangers inherent in these intersecting challenges.…”