SINGAPORE - There were four new cases of locally transmitted Covid-19 infection on Saturday (April 17), one of which involved a national serviceman who was due to attend his in-camp training (ICT) at Nee Soon Camp.

Two of the new cases are linked to a National University of Singapore (NUS) senior research fellow from India who was confirmed to have Covid-19 on Thursday.

On Saturday, the Health Ministry (MOH) said his colleague - a 31-year-old Swiss woman who is also a senior research fellow at NUS - had caught the virus too.

She had interacted with him on April 12 and developed a sore throat on April 15 but did not seek medical treatment. As she had been identified as a close contact, she was placed on quarantine. Her test came back positive on April 16, and her serology test result is pending, MOH said.

The man's 35-year-old brother, who works at DBS Bank at 2 Changi Business Park Crescent, was also infected. He had been working mostly from home, and last went back to his workplace between April 6 and 9.

As he had also been identified as a close contact, he was placed on home quarantine on April 15.

He developed a fever the next day and was taken to the National Centre for Infectious Diseases (NCID) after he informed MOH of his symptoms. His test came back positive on April 17. MOH said his serology test result is pending.

Another case reported on Saturday was that of a Singaporean man, 35, who works as a freelance photographer. He was tested on April 15 as part of the Singapore Armed Forces' protocol to test national servicemen at the start of their in-camp training.

His pooled test came back positive, and a swab done on April 16 gave the same result. He was taken to the NCID, where he developed a fever on the same day.

MOH said his serological test result has come back positive, which is indicative of a past infection.

A Ministry of Defence spokesman said immediate and thorough disinfection of the premises that the serviceman had been in was carried out.

All personnel identified as close contacts during the ICT were also swab tested. None tested positive and are under quarantine.

"They will be monitored and re-tested to confirm their negative status before they are released from quarantine," the spokesman added.

The fourth patient is a female Singapore permanent resident, 41. She is an accountant at OM Universal at 11 Kaki Bukit Road 1 but had not gone to the office since she developed a cough on the evening of April 14 after work.

She went to a clinic the next day, where she was tested for Covid-19. The result came back positive on April 16 and she was taken to NCID.

One of her household contacts is a work pass holder who arrived from India on April 2, and had tested positive for Covid-19 on that day. But he was later assessed to be a recovered case, based on his serology result on April 4.

MOH said that epidemiological investigations are ongoing and in the meantime, all the identified close contacts of the cases, including their family members and co-workers, have been isolated and placed on quarantine.

There were also 35 imported cases on Saturday, taking Singapore's total to 60,808.

All 35 had already been placed on stay-home notice (SHN) upon arrival in Singapore.

Overall, the number of new cases in the community has increased from two in the week before to seven in the past week.

The number of unlinked cases in the community has also increased from two in the week before to four in the past week.

With 17 more cases discharged on Saturday, 60,448 patients have fully recovered from the disease.

There are currently 62 confirmed cases who are still in hospital. Of these, most are stable or improving, and two are in critical condition in the intensive care unit.

Another 253 are isolated and cared for at community facilities.

Singapore has had 30 deaths from Covid-19 complications, while 15 who tested positive have died of other causes.