Towers 1, 2 and 3 were sealed off on Saturday after a Cathay Pacific pilot, who lives in the development, tested preliminary positive for a mutant variant of the coronavirus. Tests showed he was carrying the L452R mutant strain, which is found in the more infectious Delta variant, among others. He had arrived in Hong Kong last Sunday.
Cathay says it is now stepping up checks on compliance at overseas stations.
Last Wednesday, health officials said two other Cathay cargo pilots had also tested preliminary positive for Covid-19 upon their return from Frankfurt on November 6. Their household members and close contacts were quarantined, including 13 close contacts and 120 students at Discovery Bay International School, where the wife of one of the pilots teaches and their two sons attend.
Sixty friends and colleagues of the other pilot were also quarantined.
Cargo pilots are currently exempt from hotel quarantine, but the government said on Friday that it would tighten infection-control measures for flight crew members. Airlines have also been asked to assign monitoring staff to ensure crew members comply with a closed-loop system when they work overseas.