Travelers walk through the departures hall at the Hong Kong International Airport in Hong Kong, China, on Tuesday, Jan 26, 2021.  (PAUL YEUNG / BLOOMBERG)

HONG KONG – Hong Kong reported one new untraceable COVID-19 variant case on Sunday at the airport, prompting health authorities to require "tens of thousands" of airport workers to get tested for the virus.

In a press conference on Sunday afternoon, Chuang Shuk-wan, head of the Centre for Health Protection’s communicable disease branch, said the new case involved a 50-year-old porter who tested positive for the L452R mutant strain. 

The patient tested negative for the virus on June 24, but another test on July 9 showed that he was positive for the L452R mutant strain

“This was the second case involving the airport and that is why we suspect transmission to have taken place at the airport,” Chuang said.

“Since those at the airport come into contact with passengers, we will subject (to testing) all airport staff who worked from 26th of June to 10th of July and (they number) in (the) tens of thousands,” she added.

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Chuang said there were 70,000 to 80,000 airport staff but she did not have the number of those who were at the areas where the patient worked. 

Airport staff who got tested from July 7-10 are exempted from the new round of compulsory testing but the others, including those who have received two vaccine doses, have to take the tests.

The patient, a resident of 1-3 Kam Fung Street, Wong Tai Sin, visited several eight restaurants and other places in Wong Tai Sin, Sha Tin, and Sham Shui Po. He also visited Ocean Park with a friend “to have a good time” on June 26.

“For people who have been to Ocean Park on the same day, they will have to be subject to compulsory testing even if they haven’t been to the same amusement rides,” she said. 

Chuang said people who visited the other places that the patient went to also needed to be tested, adding that the  patient’s 90 close contacts were quarantined. 

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“Because it’s a variant strain, we are very concerned. We like those who stayed at the same place and at the same time (as the patient) to get tested,” Chuang said.

“The patient was a porter in the terminal area. He carried goods on and off aircraft but did not come into contact with passengers,” she added. 

Chuang said the patient tested negative for the virus on June 24, but another test on July 9 showed that he was positive for the L452R mutant strain.    

Chuang added that he received his first vaccine shot on July 1 but health authorities are still unsure whether he got infected before or after that date.