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Concerns raised over self-swab method of mass tests

2020-08-07 HKT 12:08
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  • Concerns raised over self-swab method of mass tests
Timmy Sung reports
An infectious disease adviser to the government has raised concerns about the accuracy of a new specimen collection method being implemented as the authorities expanded Covid-19 screening to more public housing estates.

On Thursday, the Home Affairs Department (HAD) announced it would extend its Covid-19 testing to include public estates in Wong Tai Sin, Kwun Tong and Tuen Mun, as well as two private buildings with confirmed cases in Yau Tsim Mong. But instead of a deep-throat saliva test, people will have to present a throat-swab they take themselves.

Speaking on Commercial Radio, Professor David Hui from the Chinese University said the switch from deep-throat saliva was probably because the government wanted to make things easier for the external testing team.

He said if the collection methods were done properly, the accuracy and value of both deep-throat saliva and throat-swab are similar.

But Wong Lei-po from the Hong Kong Molecular Pathology Diagnostic Centre was more sceptical.

Wong told an RTHK radio programme that the elderly and children may have difficulty collecting the samples on their own because of the strong body reaction it would trigger.

He also said he was afraid that the samples would not be as sensitive, and in some cases could come back as false negative.

Dressed in protective gear, personnel from the Tung Wah Group of Hospitals – which are helping with mass testing – were seen handing out throat-swab kits to residents at Tsz Oi Estate in Tsz Wan Shan on Friday morning.

The instructions on the kit advised the users to use the swab the back of the throat three to five times and put it inside the sample bottle provided. Residents can return the samples to Tung Wah staff between 7am and noon on Saturday, and if they don’t receive a phone call, it means they have tested negative.

Staff were also seen explaining the test instructions to residents, and there were also computer screens at the entrances of some buildings demonstrating how to do the throat-swab test.

One resident, surnamed Lee, told RTHK that elderly people might need help to do the throat-swab tests properly, especially those who live alone.

He also said the government acted too late to expand testing to his estate, saying that there were at least four confirmed cases in his estate, and that testing for the area should have been done in one go.