The coronavirus Alpha variant detected in a Hong Kong teenager may come from “overlooked” imported cases, a health technology scholar has said. The comment came after the government ruled out links to the Shenzhen cluster and previous cases of mutated strains reported locally.
Hong Kong’s 42-day streak of zero untraceable Covid-19 infections ended on Saturday, when a 17-year-old girl tested positive for the Alpha variant – first identified in the UK. Her mother was among the seven new infections registered on Sunday, while her 20-year-old sister received a positive result in preliminary testing.
Dr Gilman Siu, associate professor at the Polytechnic University’s Department of Health Technology and Informatics, said on an RTHK radio programme on Monday that the teen patient may have contracted the mutant virus from imported cases that the authorities overlooked.
Siu said genetic tests showed the Covid-19 variant detected in the secondary student had more than 10 genetic mutations from the variant strains found in Hong Kong earlier. It meant the possibility of a direct transmission from previous patients to the teen could be ruled out, he said.
“It is possible that [the variant came from] new imported cases that we overlooked, leading to a community infection,” the PolyU scholar said.
Fifth wave fears
The Centre for Health Protection (CHP) said on Sunday that the public health laboratory found that the genetic sequence of the teen’s variant “were not similar” to the Alpha variant genomes from previous confirmed cases reported in the city.
They also compared the variant in question to the strains of recent coronavirus cases in Shenzhen – the result again showed they were not similar.
Siu said his team at PolyU and the local health authorities are now “competing against time” to identify the source of infection of the highly transmissive variant and to curb the spread. He warned that, if Hong Kong sees other local cases or multiple parallel transmission chains, a fifth wave of the pandemic may be imminent.
“This is a very critical moment, so far we have seen her close contacts testing positive. When we see other local infections, it means this infection chain has entered the community,” he said.
The teenager carrying the Alpha variant was said to have a high viral load. She lives in Tin Shui Wai and had no travel history. She last visited her school – Queen Elizabeth School Old Students’ Association Tong Kwok Wah Secondary School – last Wednesday. The school had to suspend face-to-face teaching for 21 days, until June 24.
So far, Hong Kong has recorded a total of 11,858 confirmed cases of Covid-19 and 210 deaths. Six of the seven infections recorded on Sunday were imported.
Siu said while genetic tests showed Guangdong was unlikely the source of infection for the teenager, Hong Kong authorities may have to review testing arrangement used in the Return2HK scheme.
“Although this time it is very clear that [the teen’s infection] is not related to cases in Shenzhen, it is still a means of importing,” he said.
The government announced on Sunday that – in addition to including areas marked by China’s National Health Commission – it will take into account the Covid-19 cases reported by mainland Chinese and Macau authorities when updating the list of at-risk-areas.
Currently, Hong Kong residents who have stayed in at-risk areas two weeks before arriving in Hong Kong will not enjoy an exemption from a 14-day mandatory quarantine. Those departing from Guangzhou are also required, starting at noon on Monday, to present a negative nucleic acid test result upon arrival they obtained within 48 hours.