SINGAPORE - Staff who were in close contact with an infected AO Service Pro employee - a 79-year-old cleaner - have undergone testing for the Covid-19 virus.

The cleaner, who works at 375 and 376 Clementi Avenue 4, was the sole unlinked case announced on Monday (June 14).

A total of nine staff were tested for the virus on Monday.

Three of them were served with a quarantine order on the same day, as they were in close contact with the infected employee. They are awaiting their test results.

The remaining six were sent for testing by the company as they were working nearby. They tested negative for the virus.

It is otherwise business as usual for the cleaning company, which employs about 550 cleaners.

AO Service Pro managing director Vincent Foo said its office capacity is capped at 50 per cent and those who can work from home have been doing so.

The infected cleaner, a Singaporean, had developed a runny nose last Saturday and diarrhoea and vomiting on Sunday.

He went to a clinic on Sunday, where he was administered both an antigen rapid test (ART) and polymerase chain reaction (PCR) test.

He was immediately isolated when his ART result came back positive for Covid-19. His PCR test result also came back positive on Sunday.

His serology test result is pending. A positive serology test would suggest that the infection is not so recent.

The cleaner received his first Covid-19 vaccination shot on June 5.

He is currently in quarantine at the Singapore General Hospital.

Another cleaning company, Hong Ye Group, currently has the largest cluster originating from a cleaning company. Employees who were deployed at Changi Business Park were among the first few cases in the cluster, which had 27 cases as at June 4.