The three confirmed patients included the 28-year-old woman who returned from the United States and tested positive upon arriving at the airport on Wednesday. Her case also triggered a lockdown at a Lam Tin building.

The woman - fully vaccinated with the German-made BioNTech/Fosun vaccine, departed for the United States on November 20, and developed symptoms of Covid on November 25.

Health authorities said she had last worked on the 10th floor of Wheelock House in Central on November 19.

Another patient is a 51-year-old sailor who arrived in Hong Kong from Japan via the cargo vessel Glory Sky on December 1. His specimen collected onboard the ship tested positive.

The sailor and another 20 sea crew members have not gone ashore after arriving in Hong Kong, and no local persons had boarded the vessel.

Health officials said the patient would be sent to the hospital for isolation treatment. At the same time, all of the remaining sea crew members of the cargo vessel have to undergo quarantine onboard the ship and conduct Covid tests.

The remaining patient is a 23-year-old woman who flew into Hong Kong from Korea on December 1. She was asymptomatic and had been vaccinated with both doses of the BioNTech vaccine in Korea in August and October, respectively.

Over the past fortnight, the SAR reported 50 Covid-19 cases, all of which were imported cases. The city is also maintaining a 56-day streak of zero local Covid cases.

The city has so far recorded 12,449 confirmed coronavirus cases since the beginning of the pandemic.