Although the government had to stamp out a Delta flare-up in June in Guangdong Province, authorities this time are dealing with a much larger spread. Since the current Delta outbreak started on July 21, the number of cases has risen to 483, more than the sum total of infections from the first five months of the year. By Tuesday afternoon, the virus had spread to 15 of the 31 provinces and autonomous regions in China.
“Once it reaches so many provinces, it’s very hard to mitigate,” said Chen Xi, an associate professor of public health at Yale University. “I think this would be surprising and shocking to the rest of the world. Such a powerful government has been breached by Delta. This will be a very important lesson — we cannot let our guard down.”
Last week, Sun Chunlan, a vice premier of China, blamed “ideological laxity” for the Delta outbreaks and urged officials to step up their prevention efforts. “We cannot relax for a moment,” Ms. Sun said.
Some public health experts in the country say it is time for China to rethink its Covid strategy. In a recent essay, Zhang Wenhong, who advises the Chinese government on dealing with Covid-19, floated the idea of following a model similar to that of Israel and Britain, in which vaccination rates are high and people are willing to live with infections.
For now, China has stuck to the same strict playbook. Across the country, the government has instructed people not to travel unless necessary. In the cities of Zhangjiajie and Zhuzhou, 5.4 million people have been barred from leaving their homes. Roughly 13 million residents in the city of Zhengzhou, the site of deadly floods in July, had to stand in line for virus testing starting last weekend.
In Nanjing, where the recent Delta cases first appeared, millions of residents have had to participate in four rounds of testing.
“It’s just torturing the masses,” said Jiang Ruoling, a resident in Nanjing, who has been tested four times in the last three weeks. Ms. Jiang, who works in real estate, said she understood the need for testing, but was still critical of officials for failing to control the latest outbreak. “The leaders are actually wasting resources and everyone’s time,” she said.
Yanzhong Huang, a senior fellow for global health at the Council on Foreign Relations, said China’s “containment-based” strategy would not work in the long run, particularly as new variants continue to emerge. “It will become extremely costly to sustain such an approach,” he said.
And yet China appears unwilling to take any chances. In Wuhan, the authorities on Tuesday started testing all 12 million residents after only three cases of the Delta variant were discovered. The cities of Sanmenxia and Zhuhai have also begun mass testing. In Beijing, where there are five infections, all train services in and out of the capital have been canceled.
The current Delta cases have been linked to a flight from Moscow that landed in Nanjing on July 10. Seven passengers on the flight were infected with the variant. On July 20, nine airport cleaners tested positive. Their infections spread quickly among people who entered the airport, a major transportation hub.
Jennifer Huang Bouey, a senior China policy expert and an epidemiologist at the RAND Corporation, said that even with strict controls, it may not be realistic for officials in China to get these latest cases down to zero. “I think they may have to prepare people for a higher tolerance of Covid,” Dr. Huang said.
Part of the challenge for Beijing is that the Chinese-made vaccines being used to immunize the country are not as effective against the Delta variant as other shots. The government says it has already administered about 1.69 billion doses. Health officials are now considering giving booster shots to people with compromised immune systems as well as older citizens.
Zhong Nanshan, a top epidemiologist, said China’s vaccines are 100 percent protective against severe disease caused by Delta, and 63.2 percent effective against asymptomatic cases. He said he was confident that the latest outbreak would be controlled in about 10 to 14 days, during which officials hope to carry out extensive contact tracing in Nanjing and several other cities in Jiangsu Province.
Three days before the airport cleaners in Nanjing tested positive, a mother and daughter and a 12-year-old girl flew to Zhangjiajie after transiting for two hours in Nanjing. In Zhangjiajie, one of China’s most popular tourism destinations, all three went to see “The Charm of Xiangxi,” a song-and-dance performance by ethnic minorities. Roughly 2,000 people were packed into the theater for the show.
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Three other tourists from Zhangjiajie later traveled to the central city of Changde, taking a river cruise with dozens of other people. About 27 infections in at least six places have been linked to the boat ride.
Cases have also spread in Yangzhou among “chess and card” rooms — poorly ventilated spaces where many older patrons gather to play mahjong, chess and cards. Local officials are offering rewards of several thousand renminbi to whistle-blowers who find and report on people who have been in these rooms.
“The situation has not yet bottomed out,” Wu Zhenglong, the governor of Jiangsu Province, said at a news conference on Sunday. “The prevention and control situation is severe and complicated.”
Han Xiaoyi, a 23-year-old resident in Nanjing, said she was furious at the way the government had initially handled the Delta outbreak in her city. Officials have allowed people to continue going to work in crowded subways and buses, she said.
Ms. Han, who works in sales, has had to take time off to stand in line for hours to get tested four times in recent days. “When it started, I felt really depressed because at first, it felt like the pandemic was far away from me,” she said. “Then suddenly, it felt like it was back in my midst.”