Nucleic acid tests with a Ct value of 35 or above no longer seen as positive cases in Hong Kong

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Neither home isolation nor community isolation will be required for such persons. However, rules for patients with positive RAT results remain unaffected.

The HKSAR government has announced the adjustment of the evaluation criteria for COVID-19 nucleic acid test results with effect from 00.00am on 16 January 2023. Test results with a cycle threshold (Ct) value of 35 or above will be regarded as negative.

This is because, according to the Centre for Health Protection (CHP) of the Department of Health, case results of COVID-19 nucleic acid tests with a Ct value of 35 or above are generally not associated with infectiousness. Thus, after assessing relevant risks, the authority has decided that all those results will be regarded as negative for purposes other than clinical management. 

As such, these relevant persons would not be regarded as confirmed cases. They would not be issued with isolation orders, i.e. no home isolation would be required, nor would they be sent to a community isolation facility. 

The adjusted evaluation criteria applies to all test results issued from 16 January 2023, regardless of whether the specimen collection was carried out on or before that day. 

The above adjusted criteria also applies to all local COVID-19 RT-PCR testing institutions recognised by the Hong Kong SAR Government, as well as free and self-paid tests conducted by community testing centres/stations, and the self-paid negative test reports can also be used for cross-boundary travelling purposes.

For persons who tested positive before 16 January 2023 by nucleic acid tests with a Ct value of 35 or above and are still holding isolation orders that are in force, the CHP will notify them by SMS before noon on 16 January 2023 that they are no longer required to undergo isolation and their isolation orders are cancelled. The Government will also arrange the discharge of relevant persons in isolation facilities in an orderly manner.

If isolated persons do not receive an active notification by the CHP, they must continue to undergo isolation in accordance with the conditions of the isolation orders until they obtain negative rapid antigen test (RAT) results for two consecutive days starting from the 4^th day after their positive test.

Separately, as there is no Ct value for RAT, which has a lower sensitivity than nucleic acid test, a positive test by RAT indicates a higher viral load. Hence, patients with positive RAT results reported will not be affected. They should continue to be isolated according to the conditions as originally stipulated in their isolation orders.

ALSO READ: Hong Kong's latest social and inbound rules Jan 2023: All you need to know

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