Shanghai’s fresh Covid-19 outbreak was caused by management oversight at a quarantine hotel, according to local authorities, exposing the challenges for China’s zero-Covid policy as it battles the coronavirus for a third year. “The virus came from an imported case polluting the environment, which led to domestic infections and spread due to regulatory oversight,” a short notice from the Shanghai government said on Friday. It further identified the area of oversight as the Huating Hotel, a designated quarantine centre for travellers from outside the mainland. The eastern metropolis of Shanghai, a bustling financial hub, was seen as a model city in China’s Covid-19 fightback, with its precise contact-tracing and pandemic prevention measures that kept public inconveniences to a minimum. However, the city of 26 million is now battling its worst outbreak since the coronavirus pandemic emerged in 2020, with more than 300 infections reported this month. Shanghai had logged only 400 cases and seven deaths in the two years before the latest wave. On Friday, Shanghai reported 11 new local cases and 64 asymptomatic infections, mostly among people already under quarantine. Only symptomatic cases are classified as “confirmed” by Chinese health authorities. Mass screening and partial lockdowns have been launched in various areas, and all middle and junior schools have switched to online learning. This comes as the rest of the country also grapples with record high cases , with more than 1,000 locally acquired infections reported on Thursday, the highest national count since 2020. More than 700 of those were asymptomatic. China has described its efforts to clamp down on the Covid-19 virus as “normalisation of epidemic control”, with officials scrambling to control outbreaks across the country. However, there are difficulties in keeping local cases low while not entirely shutting the door to the outside world. Premier vows China’s Covid-19 strategy will save lives and supply chain Shenzhen in southern Guangdong province has faced repeated outbreaks since January, as the pandemic hits new highs in Hong Kong next door. Local authorities have reported cases among quarantine hotel staff, and a rise in imported infections. Several cities in Guangdong are also offering huge cash rewards for tip-offs on stowaways or illegal entrants from Hong Kong, where the caseload on Friday was close to 29,400. Professor Jin Dong-Yan, a molecular virologist with the University of Hong Kong, said the tracing of the new Shanghai outbreak to an isolation hotel showed that “quarantine or isolation is not a guarantee” of remaining coronavirus-free. It was difficult to maintain zero-Covid policies and keep the door open to the outside world at the same time, he said. “It’s very challenging, a dilemma.” Jin drew comparisons to Hong Kong, once also regarded as a role model in the fight against Covid-19. There were now lessons to be learned, he said, including vaccinating the elderly as a priority. The mainland might also be forced to change its stance, he said. “Today they announced that they are going to recognise the rapid antigen test immediately … If they learned the lesson from Hong Kong , that would be a very positive sign. In Hong Kong, the rapid antigen test played a major role [in detecting cases].” On Friday, the State Council announced that rapid antigen tests would be accepted as a supplement to Covid-19 nucleic acid tests, to “further optimise coronavirus screening strategies” in mainland China. It would be used for speedy diagnosis at community clinics, for people under quarantine or those who need to self-screen.