One more member of a coronavirus-hit Tsuen Wan family was confirmed as infected on Thursday, with health authorities in Hong Kong moving to test thousands of people to find out the extent of the virus’ spread. A 62-year-old grandfather became the city’s 1,051st confirmed Covid-19 patient, the third person from a new cluster that broke Hong Kong’s streak of 23 days without a local case. While reporting the latest Covid-19 situation locally, Dr Chuang Shuk-kwan, of the Centre for Health Protection, gave the biggest hint yet that Hongkongers would have to learn to live alongside the pathogen. Chuang said the three cases involving the family showed there might be undetected transmission of the virus in local communities. “If the whole world is like that, it will be immensely difficult to get [the virus] under control,” she said. “That’s why I say we will have to coexist with this virus.” The World Health Organisation had said on Tuesday that the coronavirus “may never go away”. Hong Kong’s virus-ravaged economy ‘may continue to suffer’ Health experts had earlier said the outbreak could be considered under control should Hong Kong have no new local Covid-19 cases for 28 days, or two incubation periods of the infection. But Chuang said that metric may no longer be relevant. “The lack of new cases may not accurately reflect the situation in society, because some people are asymptomatic,” she said. More than 200 patients in Hong Kong had shown no symptoms. Chuang said the grandfather, who also had no symptoms, had initially been sent to a quarantine centre. But his saliva sample later tested positive and he was transferred to Princess Margaret Hospital in Kwai Chung. He worked at a makeshift stall on Market Street in Tsuen Wan, where he fixed watches. He was screened after his wife, 66, was confirmed to have the coronavirus on Tuesday . A day later, the couple’s five-year-old granddaughter was announced as infected too. Business travellers are ‘top priority’ for Hong Kong economy’s relaunch Chuang said authorities had yet to identify the source of infection. “We will enlarge the area [of contact tracing] and try places including where they did not have any close contacts,” she said. Before she was admitted to hospital, the grandmother had been to the market on Lei Muk Shue Estate, Tsuen Wan, where the couple live. Staff at the stalls she visited were expected to be screened, as well as residents of Block 5, where the couple live, and residents of the nearby Cheuk Ming Building, where the child stayed. A total of 860 households involving thousands of residents were set to be tested on a voluntary basis, as well as staff and students at a learning centre that the five-year-old had been to. Chuang said government officers had been to the relevant buildings to distribute sample containers on Thursday. About 100 containers had been given to residents so far. “Some people may not have been at home, and there will be letters for them to collect the bottles from an office,” she said. Meanwhile, the government also planned to offer free Covid-19 testing to up to 500 staff per day at Hong Kong International Airport, starting on Friday . Chuang said the aim of the scheme was to confirm whether this group of people were exposed to higher risk of infection and uncover potential cases. The Department of Health will set up a service point at the airport to give out and collect sample containers from staff, who they said were at higher risk of contracting the virus because of more frequent contact with international passengers. Help us understand what you are interested in so that we can improve SCMP and provide a better experience for you. We would like to invite you to take this five-minute survey on how you engage with SCMP and the news.