The Ministry of Health (MOH) said in a statement on 21 December that a suspected Omicron cluster has been detected at Anytime Fitness in Bukit Timah Shopping Centre.
Two cases linked to the gym have tested preliminarily positive for the Omicron variant while a third case is still awaiting results.
All three of the cases are fully vaccinated and they have mild symptoms.
MOH added that they are ring-fencing the cases and contact tracing is underway.
The trio comprises an 18-year-old female student from Ngee Ann Polytechnic who was last in school on 15 December, a 21-year-old male student at Sdunrice GlobalChef Academy who had not been to school recently, and a 24-year-old male who is unemployed.
All three of them had no recent travel history.
Investigations revealed that they had visited the gym between 15 December to 17 December and all staff and visitors to the gym who are identified to be close contacts of the cases will be quarantined.
Other visitors who have been to the gym between 15 to 176 December will be issued a Health Risk Warning.