Hospital Authority discovers suspected contamination in a batch of flocked swabs
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The Hospital Authority (HA) today (May 10) announces an event of the discovery of suspected contamination in a batch of upper respiratory tract flocked swabs:
The Princess Margaret Hospital (PMH) laboratory recently conducted routine testing on a batch of three-in-one (viral transport medium and flocked swabs) specimen collection kits and detected anomalies, with subsequent testing revealing weak positive results for COVID-19 in some flocked swab samples. The HA takes this event very seriously and, upon receiving the report from PMH, a series of measures have been implemented immediately to ensure patient safety and testing accuracy:
- Immediate suspension of all flocked swabs from this supplier and arrangement of alternative flocked swabs from other suppliers;
- Enhanced sampling and testing of the supplier's specimen collection kits delivered in January this year that had previously passed routine sampling tests; and
- Review of test results of patients who had used the affected flocked swabs.
The HA conducted repeated testing on 100 samples from the same Lot of flocked swabs, ultimately identifying 18 samples that showed weak positive results for COVID-19.
The flocked swabs were procured from a local supplier and delivered to the hospitals under the Kowloon West Cluster (KWC), including Caritas Medical Centre, Kwai Chung Hospital, North Lantau Hospital, PMH and Yan Chai Hospital (YCH) from January to the end of April this year. Since the flocked swabs were sealed in packaging, the HA's microbiology experts, after analysing the test results, estimate that the flocked swabs were contaminated before delivery to the hospitals.
In addition, the HA has reviewed the patient cases that used these flocked swabs for COVID-19 testing from January this year onwards. A 91-year-old female patient admitted to PMH and an 82-year-old male patient admitted to YCH were identified as likely false positive. Both patients had CT values above 38, showed no obvious respiratory infection symptoms, and were immediately tested negative on repeated testing by doctors. No antiviral medication was prescribed, and both patients have been discharged earlier. The hospitals have informed these two patients about this event.
After consulting microbiology experts, the HA has determined that the residual virus on the contaminated flocked swabs is biologically inactive and non-infectious, and there is no health risk to patients who have undergone testing with these flocked swabs.
Records show that approximately 27 000 flocked swabs from the lot concerned were used in KWC. Besides the two possible false positive cases mentioned above, no other unusual cases were identified. The recent COVID-19 positive rates in KWC remain comparable to other hospital clusters.
A spokesperson stated, "The HA is following up on this event stringently and has notified the Department of Health (DH). We have demanded the supplier of the flocked swabs concerned to thoroughly investigate its quality control and testing records, provide an explanation, and implement remedial measures. The HA does not rule out taking further action to hold the supplier accountable."
The flocked swabs concerned are BABIO Lot No. 24090511, primarily supplied to the hospitals under KWC. This event does not affect patient clinical treatment or testing services.
The HA will continue to closely follow up with DH and the supplier. The supplier will be required to provide quality control records and testing certifications in the future to prove that their testing supplies meet with the stringent requirements so as to ascertain patient safety and testing accuracy.
Ends/Saturday, May 10, 2025
Issued at HKT 13:36
Issued at HKT 13:36
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