Health authorities have imposed travel restrictions in Guangdong and mass testing is under way as they scramble to contain a Covid-19 outbreak in the southern Chinese province, where a fast-spreading strain first found in India has been detected. Twenty new locally transmitted cases were confirmed on Sunday – 18 in Guangzhou and two in neighbouring Foshan, the Guangdong Health Commission said. That brings the total to 47 cases, 21 of them asymptomatic, since the outbreak began on May 21. A lockdown is in place in the worst-hit area, a district of Guangzhou, and from 10pm on Monday anyone who wants to leave the province must show a negative test result from within 72 hours before departure. Nearly 500 flights had been cancelled at airports in Guangzhou and Shenzhen – the third city to report cases in the latest outbreak – as of Monday morning. Meanwhile, residents of some Guangzhou districts have been told to get tested and large-scale screening is also under way in Foshan and Shenzhen. Guangzhou officials have also suspended the city’s public Covid-19 vaccination programme to focus on priority groups. China’s cabinet, the State Council, has sent disease prevention and control experts to Guangdong to help with the outbreak, National Health Commission spokesman Mi Feng said on Monday. The provincial Communist Party boss, Li Xi, has also been highly visible checking on quarantine arrangements and the vaccination roll-out. Curbing the spread of the virus – which has been largely under control in China – is a priority for leaders ahead of the party’s centenary in July and a key session next year that could see a leadership reshuffle. In Guangzhou, home to more than 18 million people, authorities have locked down parts of Liwan district, where there have been 21 locally transmitted cases. Public venues have been closed and residents subject to stay-at-home orders must rely on government deliveries of groceries and essential items. No one can enter or leave the affected areas, as interior designer Yang Rui found out when she tried to go to work on Saturday morning. “The convenience stores were still open at noon, so I bought some bottles of water but they’d sold out of instant noodles,” the 28-year-old said, adding that she had enough supplies at home for now. “I’m very annoyed that this community has been closed down with no notice.” Guangzhou residents queue for jabs after four Covid-19 cases reported Another Liwan resident, Zhong Yangyang, lives in part of the district that was shut down on Wednesday. “No one has told us what to do, we were able to buy food online but then suddenly it couldn’t be delivered,” she said. “For four days no supplies got in … we’re willing to cooperate to fight the outbreak but we need supplies.” The 22-year-old said she was now waiting for the government’s food pack delivery. The Guangdong outbreak has been traced to a 75-year-old woman who reportedly dined with friends at a dim sum restaurant in Liwan while infectious. Local media reports have described the rate of spread as “alarming”. Most of the cases identified in Guangzhou have been found to share the same DNA sequencing as the highly infectious strain found in India. Residents of Liwan have been ordered to get tested every two days, and the mass testing programme has been expanded to cover Yuexiu, Haizhu, Tianhe, Baiyun and Panyu districts. Guangzhou’s deputy mayor Li Ming on Monday said that of 3.4 million tests carried out in the past few days, just 11 were positive. He expected that number to rise as more people got tested in the coming days, but said shutting down parts of Liwan should help curb the spread of the virus. “Most of the cases have come from two communities in Liwan district and these cases share identical DNA sequencing. This strain has a short incubation period, it spreads fast and it’s associated with a high viral load,” Li said. “Its transmission route is under our control.” He said suppliers were being mobilised so that residents could get essentials while they were under stay-at-home orders. Li also said more than 13 million vaccine doses had been administered in Guangzhou, and over 3.2 million people were fully vaccinated. As of Sunday, the province had recorded a total of 2,455 cases – 1,033 of them imported – since the pandemic began, with 64 people being treated in hospital at present.