The Centre for Health Protection is investigating the epidemiological linkage of two imported cases.

The latest whole genome sequencing analysis revealed that cases 12388 and 12404 have identical genetic sequences, suggesting they are very likely to be epidemiologically linked.

Both cases stayed at Regal Airport Hotel located in Chek Lap Kok for compulsory quarantine after arrival in Hong Kong from abroad. They stayed in rooms opposite to each other on the fifth floor.

Case 12388 arrived in Hong Kong on November 11 and checked in the hotel on the same day. His specimen taken on November 13 tested positive with a Ct value about 18 and he was sent to hospital on November 14.

Case 12404 arrived in Hong Kong on November 10 and checked in the hotel on the same day. While his specimens taken on November 12 and 14 both tested negative, his specimen taken on November 18 tested positive with a Ct value about 19 and he was sent to hospital on the same day.

The centre collected environmental samples at the hotel rooms and the common area at the corridor of that floor on November 19.

Out of the 87 samples collected, 25 tested positive, among which 20 were taken from room 5111 concerning case 12404 and five were taken from room 5112 concerning case 12388.

In accordance with the whole genome sequencing results, the centre conducted site inspection at the hotel with the relevant government departments and experts to further investigate and examine if environmental factors were involved in the infection of the cases.

Opinions from experts suggested that case 12404, who had stayed in the room opposite to the room where case 12388 had stayed, might have been infected with the virus while air flowed to the corridor when case 12388 opened his hotel room door without wearing a surgical mask, coupled with unsatisfactory air flow.

To increase infectious disease control, the centre will contact and arrange for people who had stayed from November 11 to 14 in the three rooms next to the left and the right of rooms 5111 and 5112 of the same hotel, ie 12 rooms in total from room 5105 to 5120, to undergo compulsory quarantine at the Penny's Bay Quarantine Centre for 14 days.