Coronavirus: Error in another lab affected 33 cases in May

In May, a laboratory here declared 33 cases as positive for Covid-19, but the results were later found to be false. The error was caused by an apparatus calibration issue for one of the test kits at the lab between May 5 and 9.

The cases included a 43-year-old Singaporean radiographer at the Singapore Expo community care facility.

Subsequent retesting at the National Public Health Laboratory confirmed that the cases were actually negative.

The Ministry of Health (MOH) also said previously that two other cases that initially had equivocal results were also retested and found to be negative.

When they had equivocal test results, they were classified as positive as a precaution and isolated.

No false negative results were found, said the MOH.

Following the incident, Associate Professor Kenneth Mak, MOH's director of medical services, said on May 12 that advisories would be issued to all laboratories conducting coronavirus tests to ensure that test results are accurate.

Prof Mak had said the laboratory that had reported false positives would "recalibrate" its test kits and revalidate test results.

This process was expected to take place over a few days, following which Singapore would return to its full testing capacity, he added.

"To safeguard this particular process of quality assurance and to make sure we avoid having false positive results coming out in the future, we have put together some advisories and guidance for all the labs involved in testing," he said.