The task force said that with the help of the police and Ministry of Defence, it established a link between the cluster at Mustafa Centre shopping mall and the Project Glory construction site as well as a number of foreign worker dormitories: S11 Dormitory@Punggol, Sungei Tengah Lodge, Tampines Dormitory Cochrane Lodge II and Toh Guan Dormitory.
Director of medical services at the Ministry of Health Assoc Prof Kenneth Mak described how some of the dormitory cases were linked to the Mustafa Centre cluster.
"We believe that the workers had visited Mustafa and they subsequently transmitted the infection to their co-workers," he said.
"Transmission most likely occurred through close contact,for example at meal times, during breaks, and also between co-workers at work due to physical proximity at work sites," he said.
Subsequently, they could have spread the infection to colleagues and friends within the dormitories, he added.
Singapore has seen a rise of COVID-19 cases at foreign worker domitories recently.