The Centre for Health Protection (CHP) said the man, 32, arrived in Hong Kong on Tuesday and tested positive for the L452R coronavirus mutation the next day.
Antibodies were found in his sample after he was hospitalised, it said.
“After examining the epidemiological, clinical and laboratory findings, this case is compatible with a re-positive case,” the CHP said in a statement, adding that the man had not been vaccinated against Covid-19.
It said all sea crew members of the Maersk Lima, the vessel he had stayed on at the Kwai Tsing Container Terminals, will be quarantined on board for 21 days.
Those who have been to the vessel will also be ordered to undergo Covid tests.
Officials also reported one imported Covid-19 infection on Friday.
The 40-year-old woman arrived from the United Arab Emirates and did not show any symptoms, they said.
Meanwhile, an untraceable local infection of an airport worker has been reclassified as being related to an imported case, with health officials saying the infected worker’s sample was genetically linked to four Covid patients from Russia.
The CHP said the airport worker probably caught the virus on a flight served by one of the Russian patients, who was a flight crew member arriving from Moscow on July 6.
“While he had no direct contact with [the Russian crew member], he had stayed and worked in the cabin for several hours of this flight where some aircrew members had stayed in the plane all along,” the CHP said.
Last updated: 2021-07-16 HKT 18:46