There were 1,037 laboratory-confirmed cases of SARS-CoV-2 infection in Hong Kong, and one probable case based on clinical and epidemiological features as of April 28, 2020. Stable numbers of sporadic and cluster cases were detected until early March when a substantial increase in the number of imported cases was observed (Figure 1). A rise in cases caused Hong Kong to implement physical distancing measures through restrictions on gatherings and closure of bars.

• 51.9% of infections have been associated with at least one of 135 known clusters
• Median cluster size was 2 and the maximum involved 106 cases
• Among the 48.1% of cases not linked to a cluster, 90% were acquired overseas