Hidden transmission of Covid mutation feared

A 27-year-old male member of an airport ground crew diagnosed with the highly contagious Covid-19 Delta variant may not be a main link, infectious disease expert Ho Pak-leung of the University of Hong Kong said, as he warned of hidden transmission at Chek Lap Kok.

The man only developed symptoms 10 days after coming into contact with three arrivals from Indonesia, Ho noted, whereas the Delta variant's median incubation period is three days.

Yet authorities believe the man contracted the deadly mutation from the Indonesians because genetic sequencing showed their viruses to be identical, and because the man and the three Indonesians were at the airport's specimen collection point at the same time on June 11.

Ho said: "I'm worried the 27-year-old man did not contract the virus directly from the Indonesian trio, but that silent carriers acquired the variant from the trio and passed it to the man." He suggested anyone who was at the collection point on June 11 take an antibody test so silent carriers can be found, as someone could have recovered without knowing they had Covid-19.

The man also worked as a part-time customer service officer at Uptown Plaza in Tai Po, where he infected a 24-year-old female colleague.

Ho said airborne transmission could have occurred at the mall if ventilation was insufficient.

But testing specialist Gilman Siu Kit-hang, from the Hong Kong Polytechnic University, said mall visitors were lower risk compared to the man's colleagues. Siu also called for repeated tests in Tai Po district to check if the variant had spread.

The Delta variant flurry came as Hong Kong yesterday recorded three new imported cases - from Britain, Indonesia and Namibia - to take the tally to 11,921, with 211 deaths.

Meanwhile, authorities announced that compulsory testing notices with deadlines yesterday and today were extended for a day as test centers, mobile specimen collection stations and vaccination centers closed yesterday morning amid the rainstorm warning.

Separately, an outreach vaccination team was deployed to Chinese Estates Holdings Limited's office at Windsor House in Causeway Bay yesterday afternoon to administer the German-made BioNTech/Fosun vaccine for over 200 staffers and tenants, including the group's 69-year-old founder, Joseph Lau Luen-hung.

Secretary for the Civil Service Patrick Nip Tak-kuen and Chinese Estates' chief executive officer Chan Hoi-wan, who is Lau's wife, inspected the process.

As of Sunday, 2.15 million citizens received at least one shot of vaccine and 1.41 million got both doses.