This photo taken from the official Facebook page of Four Points by Sheraton hotel in Tung Chung shows the exterior of the hotel.

HONG KONG – More than 50 people who have undergone quarantine or are currently in isolation at a Tung Chung hotel have to be sent to a government quarantine facility as the authorities suspected a man who stayed in the hotel had spread the virus to another resident.

According to the Centre for Health Protection, a 56-year-old man flying in from the United Kingdom checked in a room on the 15th floor of Four Points by Sheraton hotel in Tung Chung on Nov 1. His specimen taken on Nov 5 tested positive and was sent to hospital the next day, the center said in a statement issued on late Friday.

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The man carried the Delta strain sub-lineage AY.4.2 and had a Ct (cycle threshold) value of about 15, meaning a high viral load.

The resident living in the adjacent room was a 62-year-old man from Thailand who checked into the hotel on Oct 22.

Hi specimens taken on Oct 24, Oct 26, Oct 30 and Nov 2 and Nov 6 all tested negative. But his specimen collected on Nov 9 tested positive with a Ct value of about 17. He was sent to hospital the following day.

Microbiologist and government advisor Yuen Kwok-yung suggested people undergoing quarantine at hotels should wear their masks properly when they open their room doors

An analysis conducted by the Department of Health's Public Health Laboratory Services Branch showed this man also carried the AY.4.2 variant. 

The CHP said that according to the latest analysis of the whole genome sequencing of the two men, they might be epidemiologically linked.

The center suspected that the 62-year-old man might have acquired the infection during compulsory quarantine at the hotel.

The center conducted a site inspection to the hotel with health experts Friday evening to investigate if environmental factors were involved in the infection of the cases. It collected environmental samples during the inspection in a bid to ascertain the possible source of infection.

As a precaution, the center arranged for people who had stayed from Nov 1 to Nov 6 on the 15th floor of the north wing of the hotel to undergo compulsory quarantine at the Penny's Bay Quarantine Centre.

Among them, some 30 people were still undergoing quarantine at the Tung Chung hotel while around 20 others had stayed there but had already completed their quarantine, according to the center.

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Speaking after inspecting the Tung Chung hotel, microbiologist and government advisor Yuen Kwok-yung said the 56-year-old patient had used a cycling machine in his room during his quarantine.

Yuen said during exercise, the man had exhaled a large amount of virus which might have flown into the next room when his neighbor opened the door.

He suggested people undergoing quarantine at hotels should wear their masks properly when they open their room doors.