The Ministry of Health (MOH) said yesterday that 33 Covid-19 cases from a laboratory were false positives due to an apparatus calibration issue for one of its test kits.
Subsequent retesting at the National Public Health Laboratory confirmed that the cases, and two more that had equivocal results, were actually negative.
No false negative results were found and immediate action was taken to rectify the situation, said MOH. The lab has stopped all tests and is working to resolve the issue.
MOH also confirmed 876 new cases, bringing the total number of cases in Singapore to 23,336.
One of the new cases was imported, the first such case in two weeks since April 26 saw two cases.
He is a 61-year-old Singaporean man with a travel history to Qatar who was placed on stay-home notice upon arriving in Singapore.
Of the new cases, 860 were work permit holders living in dormitories and 11 lived outside them.
A total of 20,961 workers in dormitories have been diagnosed with Covid-19 so far, or about 6.5 per cent of 323,000 such workers.
MOH said such cases continue to rise because workers who are well and asymptomatic are also tested as part of a process to verify and test every worker. "We had started this intensive testing at the purpose-built dormitories, and are now doing so for the factory-converted dormitories," it added.
MOH also identified five new clusters. They are: construction sites in 15 Serangoon North Avenue 1 and Tanah Merah Coast Road, 9 and 11 Woodlands Industrial Park E1, and 515 Yishun Industrial Park A.
Update on cases
NEW CASES: 876
Work permit (WP) holders in dormitories: 860
Work passes: 2
Visit passes: 0
WP holders outside dorms: 11
CASES TO DATE
WP holders not in dorms: 466
WP holders in dorms: 20,961
In ICU right now: 22
Deaths from Covid-19: 20
A cluster at a construction site in 6 Battery Road has been closed as there were no new links for 28 days.
Of the new cases, 98 per cent are linked to known clusters, with the rest pending contact tracing.
Three new cases are Singaporeans and permanent residents - the imported case, one linked to the Mustafa Centre cluster and another to Acacia Home at 30 Admiralty Street.
Another 425 patients have been discharged from hospitals or community isolation facilities and have fully recovered. In all, 2,715 have fully recovered and been discharged. There are 1,097 who are still in hospital, with 22 in intensive care.
The remaining 19,498 are at community isolation facilities, which house Covid-19 patients who have mild symptoms or are clinically well but still tested positive.
So far, 20 people have died from Covid-19 complications here and six others who tested positive have died from other causes.
Local cases excluding dormitory residents and other work permit holders fell to an average of nine daily in the past week, from 11 two weeks ago. The number of such cases that are unlinked has also dipped to an average of four a day from five over the same period.
Singapore now has the highest number of confirmed coronavirus cases in South-east Asia.
The Republic took 13 weeks from the first reported case on Jan 23 to cross 10,000 cases on April 22, but just two weeks to reach 20,000 cases on Wednesday. The spike is largely driven by a rise in cases of migrant workers living in dormitories.