Coronavirus: Are antibody tests the best indicator of immunity against infection and who should have quarantine time reduced?

Vaccinated arrivals who test negative for the virus and carry antibodies will soon be allowed to leave quarantine after seven days

But jury remains out, with no clear consensus in the scientific community on whether antibodies guarantee immunity to the virus

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An image from a scanning electron microscope shows the coronavirus as golden round dots emerging from the surface of cells cultured in a lab. Photo: AFP

Published: 8:15am, 23 Jun 2021Updated: 2:53pm, 23 Jun 2021

A Covid-19 antibody test will be a determining factor for whether fully vaccinated travellers have their mandatory quarantine period in Hong Kong halved to seven days starting later this month.

But scientists still cannot conclusively agree on whether the presence of antibodies gives a person immunity to the coronavirus.

While government advisory experts support the idea of reducing the amount of time fully inoculated people with the antibodies who also test negative for the coronavirus must spend in quarantine, at least one doctor has argued that the relationship between antibodies and protection against Covid-19 remains unclear.

Under the plan announced on Monday, the shorter quarantine will cover travellers returning from medium risk and high-risk countries. Taiwan has not officially been included in group B, or high-risk places, but faces the same entry requirements and is covered by the change.

Respiratory medicine expert Dr Leung Chi-chiu. Photo: Xiaomei Chen

Government experts said the aim of the antibody test was to “show evidence of response to vaccination” and to help identify any false negative cases that could not be picked up by a nucleic acid test.