Even as the number of Covid-19 infections in foreign worker dormitories continues to increase, the situation is better than originally expected, said infectious diseases expert Alex Cook.

"When we did models of the number of cases in foreign worker dorms in the early period, they had all the classical hallmarks of an exponential growth," said Associate Professor Cook on The Straits Times' weekday talk show The Big Story.

"The models suggested it was growing almost out of control, without any mitigation efforts," he said yesterday.

"What we've been seeing over the last few weeks is that the number of cases is consistently lower in reality than what the models say it should have been."

Prof Cook, the vice-dean of research at the National University of Singapore's Saw Swee Hock School of Public Health, said there were two ways to interpret this.

"You could be pessimistic and say that we are not able to detect all the cases because of the lack of capacity," he said.

"But you can also be optimistic and say it looks as if, because we're making efforts to separate the workers who are infected from those who are not, that should be bending the curve downwards."

This means Singapore is reducing the number of new infections but potentially spreading them out over a longer duration, Prof Cook added.

Cases of Covid-19 involving foreign workers staying in dorms have been rising steadily since early last month. Such cases now make up almost 23,000 of the 25,346 confirmed infections in Singapore.

On Tuesday, National Development Minister Lawrence Wong said about 32,000 of the 323,000 foreign workers staying in dorms have been tested so far.

He said about 3,000 tests are being done in the dorms each day, with that number expected to rise in the coming weeks.

Mr Wong added that all workers staying in dorms will eventually be tested for Covid-19 to ensure they are free of the virus before they resume work.

Prof Cook said yesterday that, on the whole, there are signs suggesting that the authorities are beginning to get the coronavirus outbreak in dorms under control.

But he cautioned that it is still "really unclear" what will happen in the next few weeks.

"Exactly how long those outbreaks will burn on for, we have no idea," he said.