The three patients came from the Philippines, Thailand and Saudi Arabia. They had received two doses of Covid vaccine before and remained asymptomatic.

A 33-year-old female foreign domestic helper arrived from the Philippines on October 29 on flight PR300. She underwent quarantine at Penny's Bay Quarantine Centre and she had received two doses of Sinovac vaccine in the Philippines on June 16 and July 14.

A 62-year-old man arrived from Thailand on October 22 on flight CX654. He underwent quarantine at Four Points by Sheraton Hong Kong Tung Chung. He had received two doses of Sinopharm vaccine in Thailand on July 1 and July 29.

The third patient is a 50-year-old man who arrived from Saudi Arabia on Tuesday on flight QR818 via Qatar. He had received two doses of BioNTech vaccine in Hong Kong on August 14 and September 4.

As for the two imported cases reported on Wednesday which involved two cargo flight pilots aged 57 and 29, the sample they submitted were found to be carrying the sub-lineage AY.43 of the Delta variant, also known as the Delta+ mutant strain.

The Centre for Health Protection noted that the strain is common in Europe, especially in Germany.

The center also found a 56-year-old man whose case was reported on Sunday, who carried the Delta+ strain, traveled from the UK on the same flight BA207 with a 62-year-old man. The latter was reported as the first Delta+ case in the city last Friday (Nov 5).

Their seats were close to each other, with seat numbers 2B and 2E respectively, and the virus strain detected in them matched as well.

The center on the other hand reminded residents and people who had been to Harbour Pinnacle on Minden Avenue in Tsim Sha Tsui to undergo compulsory testing by tomorrow (Nov 12).

A total of 39 cases have been reported in the past 14 days and all of them are imported cases. The city's Covid tally now stands at 12,378.