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A Hong Kong resident undergoes coronavirus testing at a mobile specimen collection station. Photo: K.Y. Cheng

Coronavirus: Hong Kong officials identify airport testing centre as probable source of Delta variant infection

  • Airport worker spent time at the sample collection centre where two arrivals with same viral footprint as his were detected earlier this month
  • 27-year-old’s case is Hong Kong’s first local infection involving the Delta variant; 4 new imported cases confirmed
Health authorities have pinned the source of a Hong Kong airport worker’s Delta variant infection to a sample collection centre at the transport hub, where two Covid-19 cases sharing the same viral footprint were previously detected.

In a groundbreaking development in the city’s first local case involving the more infectious variant, the Department of Health on Friday said whole genome sequencing results showed the 27-year-old worker’s infection was identical to that of three arrivals from Indonesia found with the coronavirus this month.

Philippines, Indonesia flight bans hit supply of domestic workers in Hong Kong

The discovery marked a step forward for officials racing to determine the source of the airport worker’s variant infection, but some experts cautioned that alternative routes of transmission could still not be entirely ruled out.

“Two of them tested positive after their samples were taken at the Department of Health’s temporary specimen collection centre at Hong Kong International Airport,” a department spokesman said, referring to the three arrivals.

“[The worker] had received cargo flight crews at the airport and stayed in the temporary specimen collection centre for work in the morning on the same day.”

The airport worker, whose case ended Hong Kong’s 16-day streak of zero local infections, was earlier on Friday confirmed as carrying the Delta coronavirus variant, first found in India.

The three people sharing his viral footprint are all domestic helpers from Indonesia, two of whom were found on June 11 to be infected, before leaving the airport. The other tested positive while quarantining in a Hong Kong hotel.

A man who works at Hong Kong’s airport has been confirmed to be carrying the Delta variant of the coronavirus. Photo: Nora Tam

Hong Kong on Friday recorded no new untraceable local Covid-19 cases, but confirmed four imported infections – two from Britain, one from Indonesia and another from Bangladesh.

The latter involved a sea crew member who was found dead on a ship arriving in Hong Kong on June 21. A postmortem examination revealed he had been infected with the coronavirus.

The city’s official case tally now stands at 11,909, with 211 related deaths.

Dr Gilman Siu Kit-hang, a Polytechnic University associate professor who studies local Covid-19 cases separately to the official analysis, also identified at least six other imported cases this month from Indonesia which carried genome sequences similar to the one found in the airport worker’s case.

New strain, new danger: how worrying is Hong Kong’s first Delta variant case?

Referring to the health department’s findings, he said the man was likely to have been directly infected by an arrival at the airport, and experienced a relatively long incubation period which only ended on June 21 when he showed symptoms such as fever and cough.

But Siu said he was puzzled by the extent of the man’s viral load in the past week.

“If he was infected on June 11 ... it has been around two weeks now. But his recent viral level was on a pretty high level, which seems to be indicative of a recent infection,” Siu said.

“It remains unclear whether there are other cases carrying the same genome sequence causing the infection.”

Professor Leo Poon Lit-man, from the University of Hong Kong, who conducted separate genetic analysis, derived similar results to the government’s.

“I agree that [the three arrivals from Indonesia] were likely to be the source of the virus,” Poon said. “But we can’t completely exclude the possibility that [the man] was infected by another source.”

The Centre for Health Protection is continuing to investigate how those infections could have been transmitted.

Poon and Siu agreed the government should look at whether current protection measures for airport staff were sufficient, with the latter questioning if personal protective equipment was being used properly.

Hong Kong detects first suspected local case of Delta Covid-19 variant

Siu also said the 17-year-old girl who was Hong Kong’s first community case of the Alpha variant was likely to have acquired the virus from animals. Her infection was confirmed on June 5.

“The virus contained lots of new mutations. To me, that virus seems to be a virus coming from the future,” Siu said.

“If it was human-to-human transmission, with such a short period [of time], the virus shouldn’t be able to develop that high numbers of mutations.”

Meanwhile, a 19-year-old girl who travelled from Hong Kong to Britain on June 13 has tested positive to Covid-19 three days after arriving in the country.

The building in Yuen Long where she lives was issued with a mandatory testing order on Friday. The teenager had been fully vaccinated with two doses of the BioNTech vaccine.

Earlier, Dr Joseph Tsang Kay-yan, chairman of the Medical Association’s communicable diseases committee, said all inbound travellers to the city should be required to be fully vaccinated if the 27-year-old’s Delta variant infection was confirmed.

He said the variant – which is more capable of binding to cells and replicating because of various mutations, such as the L452R one found in Hong Kong – had become increasingly prevalent around the world.

The Delta strain’s virulent nature would make it increasingly difficult for the government to calibrate its ban on flights from high-risk places, Tsang said.

With Hong Kong on edge over Covid-19 variants, here’s what you should know

“But if all the passengers on the plane have been vaccinated, it can reduce the risk of infections,” he added.

“Also, one wouldn’t have to ban flights all the time,” he said, referring to the safety mechanism that suspends flights from airlines that had brought infected passengers to the city on a recurring basis.

Tsang added it would only work if all passengers had received both jabs and waited for full immunity to kick in.

After the 27-year-old Tai Po resident’s case was confirmed on Thursday, authorities ordered into quarantine 180 people identified as his close contacts, as well as that group’s own close contacts.

Professor Gabriel Leung, dean of the University of Hong Kong’s (HKU) medical school, on Thursday said the Delta strain was “many times more worrying” because of its high transmissibility.

It is about seven times more transmissible than the original strain first detected in Wuhan, meaning each infected person with the Delta variant can, on average, spread it to between six and eight others, compared with the two or three transmissions associated with the original.

HKU microbiology expert Ho Pak-leung, meanwhile, criticised those who had yet to be vaccinated. “Society is paying the cost for them,” he told a Friday radio show, adding the new case was likely to delay the relaxing of social-distancing measures and reopening of the border with Macau and mainland China.

Tsang, of the Medical Association, said research had shown that the German-made BioNTech vaccine remained effective against the Delta variant despite somewhat reduced efficacy.

He said 88 per cent of those fully vaccinated with that vaccine avoided even mild symptoms, while 96 per cent could be shielded from severe complications.



This article appeared in the South China Morning Post print edition as: Airport testing centre identified as likely source of Delta variant case
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