A 64-year-old cleaner at the airport has tested positive for the virus, and health officials suspect he may have the highly contagious Omicron variant.
His work involved cleaning a toilet designated to be used by travellers who test preliminary positive for Covid-19 and are waiting to be taken to hospital.
An overnight lockdown of the man’s residential building, On Hei House in Tuen Mun, found no new cases.
The Centre for Health Protection (CHP) said more than 50 people had been sent into quarantine in connection with this case which it described as import-related.
Meanwhile, there were four new imported cases involving people who flew in from Australia, Ghana, Nigeria and Germany.
The CHP also said that genome sequencing has confirmed seven more Omicron cases among imported Covid-19 infections reported earlier this week.
Hong Kong has so far reported 41 imported Omicron cases.