The first indication of human-to-human transmission in Singapore was detected 11 days after confirmation of the first imported case. China imposed a lockdown of Wuhan on Jan 23, 2020, and suspended all outgoing tour groups beginning Jan 27, 2020. Despite these measures, local clusters were subsequently identified in Singapore, with probable links to travellers from China before the measures to curb travel were implemented. Although the primary case or cases in all three clusters cannot be conclusively identified, they are postulated to be tourists or business visitors from China. The tour group implicated in cluster A originated from Guangxi at a time when relatively few cases had been reported in that region of China.13 Temperature screening for inbound travellers on flights from Wuhan was implemented in Singapore on Jan 3, 2020, and expanded to all flights from China on Jan 22, 2020. Nonetheless, it is unlikely that these primary cases could be identified by temperature screening, because there was no indication that they were febrile on arrival.