Singapore saw its sharpest single-day spike of 728 new coronavirus cases yesterday, bringing the total number of cases here to 4,427.
While the spread of the virus in the wider community has held steady over the past two weeks, the number of cases linked to foreign workers in dormitories has risen exponentially over the past two weeks, accounting for 654 of yesterday's new cases.
This takes the number of infected workers linked to dormitories to more than 2,600, or about 60 per cent of cases here.
The bulk of the cases are in large purpose-built dormitories - 19 of the 43 such dorms have clusters. But there are also 12 clusters at smaller factory-converted dormitories.
On the other hand, no imported cases have been announced since April 9 - a sign that progressive travel restrictions and measures requiring returning travellers to serve their 14 day stay-home notice at government facilities have paid off.
With the addition of four more dormitories in the past two days, a total of 12 dormitories have now been declared isolation areas. Workers at these lodgings must be quarantined in their rooms for 14 days.
Associate Professor Alex Cook, vice-dean of research at the National University of Singapore's Saw Swee Hock School of Public Health, said the sharp spike in new cases among work permit holders could be attributed in part to efforts to undertake more active testing of the workers.
Transmission is also more likely to occur in cramped quarters such as dormitories, he added.
"Although we are seeing 600-over cases (in dorms) today, it is quite likely that we are going to see substantially more tomorrow and over the weekend... If you just extrapolate from the growth in numbers we have seen over the last two weeks, it will not be at all surprising if by the end of April, we hit 10,000 to 20,000 cases at least."
He said that to bring the situation under control, dormitories should be less densely populated, more workers should be tested and those with symptoms should be isolated.
Efforts to this end are already under way as dormitories with cases are being locked down and steps are being taken to prevent clusters forming in dormitories where no infections have been reported.
Essential workers are also being moved out of factory-converted dormitories, so isolation facilities can be created with this vacated space.
Prime Minister Lee Hsien Loong, who was in a video conference with staff from the Ministry of Manpower and members of the inter-agency task force providing support to foreign workers and dormitory operators yesterday, said on Facebook that he was encouraged to learn that the workers recognise the Government's collective efforts and are working with them.
He added that he was grateful for the workers' contributions.
"Foreign workers have helped us to build HDB towns, MRT lines, airports and ports. Some man midnight shifts in our factories... We will work with them, especially those living in the dorms, to see through this difficult period."
Meanwhile, within the local community, cases of new coronavirus infections - which were averaging 37 a day over the past week - hit 48 yesterday. Experts said this was a reminder that residents should not become complacent about the outbreak.