Four COVID-19 cases were preliminarily confirmed by a private laboratory in the Targeted Group Testing Scheme arranged by the Transport Department and were sent to the Department of Health (DH) for confirmatory testing according to established procedures.

The Government made the statement today in response to reports that three taxi drivers and a rehab bus driver who were confirmed COVID-19 cases earlier, subsequently tested negative after being followed up by the Hospital Authority and have been discharged from the hospital.

The four cases, preliminarily confirmed by KingMed Diagnostics (Hong Kong) as one positive and three "indeterminate", were sent to the DH’s Public Health Laboratory Services Branch and subsequently confirmed as positive cases.

The test results at that time showed that the viral load of the specimens was very low. These cases later tested negative for the virus and met the discharge criteria. As a result, the people concerned were arranged to be discharged.

This does not affect the confirmation as positive cases earlier, the statement noted.

The Government said that KingMed Diagnostics (Hong Kong) has participated with satisfactory performance in the external quality assurance programme of the DH, and has the medical testing accreditation of the Hong Kong Laboratory Accreditation Scheme.

It added that the Public Health Laboratory Services Branch of the DH has been designated by the World Health Organization (WHO) this year as the WHO COVID-19 Reference Lab and WHO COVID-19 external quality assessment programme provider.

The Public Health Laboratory Services Branch also provides a quality assessment programme for local laboratories.

Taking into account that multiple cases tested positive at the same time, follow-up investigations have been conducted and so far no definite evidence has been found that cross-contamination of specimens occurred during the process.

The Public Health Laboratory Services Branch has also provided some suggestions to the private laboratory in accordance with good laboratory practice.

The Government emphasised that it will closely monitor the quality of service provided by the laboratory to ensure its service quality.