A new Covid-19 cluster of 13 cases at Block 506 Hougang Avenue 8 was announced by the Ministry of Health (MOH) yesterday.

The latest case is a 58-year-old Singaporean housewife, which brings the total number of cases in the cluster to 13.

The woman, who was among the 35 cases reported in the community yesterday, received her first dose of Covid-19 vaccine on May 18.

The new Hougang Avenue 8 cluster includes a sub-cluster of four cases linked to a 67-year-old retiree who was confirmed to have the virus on May 26.

The Hougang Avenue 8 cluster was first detected when a 57-year-old unemployed woman who lives in the Hougang block was confirmed to have the virus on May 15.

MOH said that since the last testing operations conducted at the block on May 21 and May 22, there have been new cases of infection in Block 506 as well as in the neighbouring blocks.

Covid-19 viral fragments have also been detected in wastewater samples collected from some of these blocks.

A total of 22 of yesterday's community cases are from the MINDSville @ Napiri cluster, which was first detected when a 37-year-old female resident tested positive for the virus on Monday.

The 19 residents and three nursing aides have been quarantined prior to their positive Covid-19 test results. The staff and 17 of the residents have been vaccinated.

This takes the total number of people linked to the cluster to 27.

Finance Minister Lawrence Wong, who is co-chair of the Covid-19 multi-ministry task force, said yesterday that the authorities were very concerned about the presence of hidden coronavirus community cases.

He added that the outbreak at the disability home was a "stark reminder of this".

There were a total of 34 linked cases yesterday, out of a total of 35 community cases.

The only unlinked case is a 41-year-old permanent resident who works as a coating inspector at SBM Keppel Tuas.

He travelled to India in July last year and returned to Singapore on April 20. He then served his stay-home-notice (SHN) at a dedicated facility until May 11.

MOH yesterday said all his Covid-19 tests came back negative during the SHN, but he was tested on June 1 as part of rostered routine testing and it came back positive on June 2.

His serology test result is also positive, which means that he has a past infection of the disease.

MOH said he has been classi-fied as an unlinked case because it cannot fully exclude the pos-sibility that he had been infected locally.

The man had received his first dose of the Covid-19 vaccine on May 24.

Yesterday, there were 10 imported cases who were placed on stay-home notice on arrival. Among them were four Singaporeans and one permanent resident.

No new cases from workers' dormitories were reported.

Singapore's total number of Covid-19 cases is now at 62,145.