Three of the four Covid-19 cases found among the workers and volunteers at the Singapore Expo community care facility have been found to be negative after re-testing.

One of them, a Singaporean radiographer (Case 20844), 43, was reported as a confirmed case on May 7.

But his case was a false positive.

Test kit issue

It was one of 33 such cases arising from an apparatus calibration issue for a test kit.

The Ministry of Health said on May 10 that 33 tests from a laboratory were found to be false positives and subsequent re-testing at the National Public Health Laboratory confirmed that these were negative cases.

The ministry added that the converse was not discovered: "There were no false negative results discovered from our review."

Immediate action taken

Immediate action had been taken to rectify the situation, the ministry said.

The laboratory has stopped all tests and is working to resolve the issue.

Verified negative

Additionally, the two other confirmed cases at the Expo facility -- a 20-year old nurse (Case 19360) and a healthcare volunteer (Case 18669), 52 -- were shown to have had "equivocal" results.

The MOH said both of them "were subsequently verified to be negative upon re-testing".

The nurse was reported as a confirmed case on May 5.

The volunteer was reported as a confirmed case on May 4.

Case 17881, who was tested positive, has been discharged on 5 May.

In total, more than 280 fellow healthcare workers and personnel at the Singapore Expo have been swabbed.

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