SINGAPORE: Thirty-three previously confirmed COVID-19 cases from a laboratory have been found to be "false positives", including a healthcare worker who worked at the Singapore Expo community care facility, the Ministry of Health (MOH) said on Sunday (May 10).
"MOH regularly reviews the laboratory tests and recently found that 33 cases from a laboratory were false positives, due to an apparatus calibration issue for one of its test kits," the health ministry added.
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Subsequent retesting of the cases at the National Public Health Laboratory confirmed that these were negative cases, MOH said.
"There were no false negative results discovered from our review," said the ministry, adding that it has taken immediate action to rectify the situation.
The laboratory has stopped all tests and is working to resolve the "calibration issue", MOH added.
A 43-year-old man, known as Case 20844, was among "false positive" cases. According to MOH's previous reports, he worked as a radiographer at the community care facility at Singapore Expo.
The man, who had no recent travel history to affected countries or regions, was previously confirmed to have COVID-19 infection on May 7 and warded at the National Centre for Infectious Diseases (NCID).
MOH said the 33 "false positive" cases are: Cases 20844, 20847, 20850, 20853, 20854, 20855, 20856, 20973, 21018, 21021, 21024, 21111, 21120, 21163, 21166, 21170, 21370, 21456, 21581, 21595, 21596, 21598, 21599, 21600, 21601, 21602, 21603, 21604, 21605, 21606, 21607, 21608 and 21609.
No details about the other cases were provided by MOH in its reports.
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TWO CASES HAD EQUIVOCAL RESULTS
MOH on Sunday also reported that two people from the public healthcare sector who worked at the Singapore Expo community care facility - Cases 18669 and 19360 - had "equivocal" results.
"All equivocal results are sent to the National Public Health Laboratory for re-testing. As a precautionary measure, we had categorised Cases 18669 and 19360 as positive while pending verification, and isolated them," MOH said.
Both were "subsequently verified to be negative upon re-testing", said the ministry.
Case 18669, a 52-year-old Singaporean woman who worked as a healthcare volunteer at the Singapore Expo facility. She had tested positive for COVID-19 infection on May 4 and was warded at NCID.
Case 19360 is a 20-year-old male Singaporean nurse who worked at the Singapore Expo facility. He was previously confirmed to have COVID-19 on May 5 and was also warded at NCID.
CNA has approached MOH for more information.