More than 20 children, staff and family members connected to a Hong Kong kindergarten were ordered to quarantine on Saturday, as a Covid-19 infection involving a four-year-old boy brought the city’s brief seven-day respite from local untraceable cases to an end. With all local schools expected to resume face-to-face classes in less than 10 days, an infectious diseases expert suggested officials reconsider the move in light of the boy’s infection, or mandate that all schoolchildren be tested for the virus. Dr Joseph Tsang Kay-yan said it was not surprising to see sporadic local untraceable cases as there were still hidden transmission chains in the community, but he hoped it did not involve the virus spreading quickly. “Whether all schoolchildren would need to undergo testing … this could give a clearer picture how big the [Covid-19 infection] problem is,” Tsang said, pointing to the fact dozens of schools had reported outbreaks of upper respiratory tract infections recently. In total there were three new coronavirus cases confirmed on Saturday, with the other two involving domestic helpers who had recently arrived from Indonesia. Fewer than five people tested preliminary-positive, all of whose sources of infection could be traced. Alert to the threat from outside the city, the Hong Kong government also said it was closely monitoring the sudden spike of cases in Taiwan, where the daily number of local infections rose to a record of 180 on Saturday. The day before, the government tightened quarantine rules for arrivals from the self-ruled island, who from Sunday must undergo isolation at one of the designated hotels rather than at home. Macau has also announced tighter rules for travellers from Taiwan, which will come into force on Sunday. Visitors will be required to undergo 21 days of medical surveillance, instead of the current 14 days plus seven days of self-monitoring. 56 per cent of Hong Kong students spent more time gaming during pandemic: survey The four-year-old’s infection meant that 17 children and some teachers from HKVNS Alumni Association Kindergarten in Ho Man Tin, which the boy attends in class K1B, would be isolated in one of the two hotels designated for quarantining the close contacts of Covid-19 patients. Dr Chuang Shuk-kwan, head of the Centre for Health Protection’s communicable disease branch, said officials would wait to see how many people were involved before deciding which hotel to use. “We’ll have to see how many people there are and their age range before deciding on which hotel,” Chuang said. “As there are a large number of kids, they will be accompanied by family members … Toys, books and necessary items will be provided to children.” According to Chuang, the boy has around five to six family members listed as close contacts, who would have eaten with him. Officials said the family did not have a helper, and his grandmothers were his main carers. His parents, who work in different restaurants, had been tested regularly, she added. Officials said the boy’s time was divided between residences in the Yee King Building in Ho Man Tin, and the Pak Tin Estate in Shek Kip Mei. “The possible transmission path might be from family members or the kindergarten,” said Chuang, who added that investigations into the source of infection were ongoing. Early last week, the government said all schools would be allowed to resume half-day face-to-face classes for all pupils from May 24. It was not the first time kindergarten pupils and teachers have been sent into quarantine after a brush with a coronavirus patient. In March, a class of 15 pupils from the Woodland Montessori Academy on Caine Road were ordered into isolation, after they were identified as close contacts of a three-year-old who contracted Covid-19. How Hong Kong’s former cabin crew members are taking off in new jobs As of Saturday, Hong Kong’s official case tally stood at 11,821, with 210 related deaths. That total figure could end up dropping by one, however, after authorities said a positive test linked to a 29-year-old worker at testing firm BGI, who was confirmed as a Covid-19 case on May 7, could be because of contamination. Chuang said the man was found with the coronavirus strain first reported in Wuhan, which had not been circulating in Hong Kong recently. “Our laboratory has conducted additional genome analysis and we found that it does not look like a case of infection,” she said. “There’s a possibility that it is a case of contamination. As to how it happened, we will have to look into it.” The man, who was vaccinated with two doses of the BioNTech jab, had not travelled to mainland China recently. Onco Medical Laboratory, which was involved in processing the man’s sample, said the contamination could not have happened at its facility. “During the process of testing, other samples handled on the same day with [the man’s] sample were not tested positive, therefore the possibility of contamination by other samples did not exist,” the company said. It added that the lab did not use a complete coronavirus strain as a control sample, suggesting that it would not be able to cause any false positive findings. The company said it attached great importance to this incident and would cooperate with the government investigation. Professor Leo Poon Lit-man, from the University of Hong Kong, who was involved in analysing the patient’s samples, said the man could have also been contaminated at his workplace.