A 39-year-old Indonesian was the lone locally transmitted case of Covid-19 confirmed here yesterday.

He preliminarily tested positive for the B117 strain, which is reportedly more contagious.

The man is a crew member on board a bunker tanker, and had not disembarked from the vessel except to go for Covid-19 testing and vaccination, said the Ministry of Health (MOH).

He did not show any symptoms and was detected when he was tested last Thursday as part of rostered routine testing.

The man's pooled test result came back positive the next day, and he was taken in an ambulance to the National Centre for Infectious Diseases.

An individual test done last Friday came back positive for Covid-19 infection the next day.

His earlier tests from rostered routine testing - the last one on April 1 - had all been negative.

His serological test result has come back negative, indicating this is likely a current infection.

While he has preliminarily tested positive for the B117 strain, further confirmatory tests are pending.

The man had also received his first dose of a Covid-19 vaccine last Thursday. However, MOH said that as the vaccine does not contain live virus, he could not have been infected due to the jab.

MOH added that it is possible for one to be infected just before or just after vaccination as it typically takes a few weeks for an individual to build up immunity after completing the vaccination.

MOH said epidemiological investigations are ongoing, and in the meantime, all the identified close contacts of the case, including crew members of the vessel, have been isolated and placed on quarantine.

There were also 22 imported cases yesterday, taking Singapore's total to 60,831.

All 22 had already been placed on stay-home notice upon arrival in Singapore and tested positive during that period.

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

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

With 22 cases discharged yesterday, 60,470 patients have fully recovered from the disease.