Visitors queue at a community testing center in Hong Kong. There are worries that the mutant virus might have slipped through. Photo: Miguel Candela Poblacion/Anadolu Agency

Hong Kong has been urged to retest previously arrived British travelers and analyze the genome sequences of any coronavirus infection to see whether the UK mutation has entered the territory.

Of 45 imported cases from the UK since early November, 85% showed no symptoms. This was a higher percentage than usual, said Ho Pak-leung, a microbiologist of the University of Hong Kong.

The government should do the gene sequencing and find out if any carried the mutated coronavirus from the UK, Ho said.

The UK mutation has 10 amino acids different from the original virus in Wuhan. Some of these new amino acids increase the infectivity of the mutated virus.

The mutated virus contained new spike proteins that could have lowered the accuracy of the current mRNA tests and resulted in some false negative results, he said.

Several thousand students who had returned to Hong Kong from the UK could have carried the mutated virus to the territory, said Leung Chi-chiu, chairman of the Medical Association’s advisory committee on communicable diseases. The government should consider testing these people again to stop possible transmission.

Children wearing masks play in Hong Kong. The city has banned flights from the United Kingdom in response to a new variant of Covid-19. Photo: Vernon Yuen/NurPhoto/AFP

The mutated virus was being spread rapidly not only in Britain but also in many other countries, he said. As it had a higher infectivity, it would probably replace the original one to become dominant variant in most places, he said.

Leung said it was not safe enough to require the previously arrived UK travelers to stay at home for seven more days. He said these travelers should be sent to a designated hotel for quarantine.

Infectious disease specialist Joseph Tsang said the government should consider banning more flights from Europe as infection numbers there spike.

The strain that emerged in the UK in September could have spread to other European countries before they suspended air travel with the UK, Tsang said.

Also, the government should extend the quarantine period for people returning from France, Belgium, the Netherlands and Denmark to 21 days – a week longer than other inbound travelers – and put them into quarantine camps instead of hotels, he added. These travelers should also be tested more often during their final week of quarantine, he said.

Meanwhile, Hong Kong is beginning to see a drop in infections, as the city reported 63 new cases on Tuesday – the lowest in a month.

The Centre for Health Protection said 53 were locally acquired, with the source of infection unknown for 13 of them.

Wu Xiaochun, a private doctor who runs a clinic in Tin Shui Wai, came down with the virus after he treated two patients on December 15 and 18 who subsequently tested positive. Staff at Wu’s clinic will be quarantined, and patients who saw him between December 19 and 20 have been asked to get tested.

Chuang Shuk-kwan, the head of the communicable diseases branch at the Center for Health Protection, said she hoped the drop in infections would continue, saying people should remain extra vigilant.

“I hope this trend will continue, but I am still not sure yet,” she said. On Tuesday, about 30 preliminary positive cases were recorded.

While the first batch of vaccines from Sinovac is expected to arrive in Hong Kong as early as next month, allergists from two concern groups said Tuesday that fears of allergy were overblown and should not deter people from getting vaccinated.

The Allergy Association and the Institute of Allergy said severe allergic reactions had been reported following Covid-19 vaccinations in other countries and substances known as excipients – which are often added to vaccines as preservatives and stabilixers – are suspected to be the cause.

“There is no real medical reason to avoid a vaccine purely on such a rare occurrence of possible excipient allergy. It’s always been here, and it’s a bit blown up,” said Philip Li from the Allergy Association.

Read: Medical expert says HK may need partial lockdown