Two SMRT train drivers and one team Manager had been infected with tuberculosis (TB).
Three of them from Tanah Merah station were infected four to six weeks back. Not everyone who is infected with TB develops TB disease.
SMRT has subsequent did TB screening for its Tanah Merah staff, yet it is not known how many of them been screened.
Dr Asok Kurup, an infectious disease specialist at Mount Elizabeth Hospital, said: “The degree of infectiousness depends on the severity of symptoms. If someone has minimal symptoms, we don’t expect them to be posing much risk.”