Chinese authorities are rushing to trace and control the country’s first widespread appearance of the Delta variant as the worst coronavirus outbreak in more than a year spreads to at least 14 provinces.
The National Health Commission reported 55 locally transmitted symptomatic infections on Monday, taking the total number of infections linked with a cluster found last month in Nanjing city, the capital of eastern Jiangsu province, to more than 250.
Although small compared with daily case counts in many other countries, climbing infections of the more infectious coronavirus Delta variant is the latest challenge to Beijing’s campaign to eradicate fully the virus within its borders.
Since March 2020, when the country first reported zero new infections, China’s health authorities have battled a series of small-scale outbreaks. Officials said the outbreaks were seeded by imported infections or contaminated frozen goods but that each had been contained within a single province.
Repeated scares of a relapse spurred a rapid rise in China’s daily vaccination rate. But Beijing has shown no sign of relaxing strict border controls, which analysts predict could remain in place into next year.
Nanjing health officials have said that the outbreak began on July 10 when cleaning staff caught the disease from a plane that arrived from Russia at the city’s main airport, a busy travel hub.
The virus then spread among airport staff working on international and domestic flights. The infections went undetected for 10 days and were only discovered on July 20. Since then, mass contact tracing and swab testing has uncovered related cases across China.
There were 40 locally transmitted cases reported on Monday in Jiangsu province, while the remaining 15 were scattered across Hunan, Hubei, Shandong, Henan, Hainan and Yunnan provinces as well as in Beijing.
Forecasts by Lanzhou University reported in Chinese state media on Monday said the case count in Jiangsu alone would hit about 425 by August 12.
A number of big Chinese cities over the weekend closed or limited entry for popular tourist sites. The capital city Beijing barred travellers from high-risk regions.
Zhangjiajie, a popular destination in central Hunan province known for its dramatic landscape of sandstone peaks surrounded by streams and waterfalls, was closed on Friday after nine confirmed cases elsewhere in China were linked back to a performance held in a packed local theatre.
The spreading event at the busy tourist destination was more worrying than the outbreak in Nanjing, Zhong Nanshan, one of China’s best-known respiratory doctors and a government adviser, said at the weekend.
Zhong added that the Delta variant’s arrival meant that authorities had to adopt more stringent tracing measures. “For the Delta variant, anyone who shares the same space, employer or building within the last four days should be considered a close contact,” he said.