“We have to closely observe those incoming travellers, we have to do repeated viral testing, including antibody testing for whoever is coming in to Hong Kong,” Tsang said.
He made the comments after the Centre for Health Protection Thursday confirmed that a 27-year-old airport worker has been infected with Covid-19, and that a specific mutation that is present in a number of variants – including Delta – was found in samples taken from the patient.
A routine sewage test taken from Tai Po also tested positive for the delta strain – which was first discovered in India and is considered by experts to be more contagious than other variants.
Tsang said a high viral load of the Delta Covid variant in sewage in Tai Po means there must be a number of sufferers there.
He added sufferers may not know they have it, because of the absence of fever.
A Wednesday lockdown of the airport worker’s housing block in Tai Po – Wan Hang House at Wan Tau Tong Estate – yielded no further positive cases even after authorities tested some 2,100 residents there.