Health authorities also reminded those at Mei Yat House, Yat Tung (II) Estate in Tung Chung to undergo mandatory testing tomorrow, as the 47-year-old waitress who works at the Cathay Pacific Lounge was at the block.

The five new cases involve four men and one woman aged between 9 months and 56 years old, arriving from the Philippines, Indonesia, and the United Arab Emirates.

Four of them are vaccinated, according to the Centre for Health Protection of the Department of Health.

The center also reported a vaccine-contaminated case involving a sample from a 32-year-old man who is suspected to have been contaminated with vaccine strains on August 16.

His throat sample, which was taken at a private clinic, tested positive with a low viral load, but he tested negative for the virus and antibodies after being admitted to the hospital.

It is known that his doctor had administered Sinovac vaccines to other people at the same location in the clinic on the same day.

According to a genetic analysis of the patient's sample by the department of microbiology of the University of Hong Kong, the virus sample matched the SARS-CoV-2 vaccine strain.

The center concluded that the case was consistent with the vaccine strain contamination and therefore would not be seen as a confirmed case.