Healthworkers give residents a second round of nucleic acid testing on January 10, Hua County, Anyang City, Henan Province. (Wang Zirui/Costfoto/Future Publishing/Getty Images)A third Chinese city has been placed under strict lockdown as the country tries to contain localized outbreaks of Covid-19, local authorities said Tuesday.That raises the total number of people now confined to their homes in China to approximately 20 million, with the Beijing Winter Olympics just over three weeks away. All 5.5 million residents of Anyang city in central Henan province are not allowed to leave their homes, while shops, restaurants and factories remain shut, the Anyang municipal government said. More than 4,000 students and staff from an Anyang school have been placed in government-run quarantine centers after nine people tested positive for the virus, local authorities added. The city has reported a total of 84 Covid-19 cases since it detected two local Omicron infections on January 8. On Tuesday, China reported 110 new local symptomatic Covid-19 cases, the National Health Commission (NHC) said in a statement. China counts asymptomatic cases separately.Strict lockdowns: Anyang is the third Chinese city after Xi’an in the northwest Shaanxi province and Yuzhou, also in Henan, to implement a full Covid lockdown. Restrictions were placed on Xi’an’s 13 million residents on December 23. In the days and weeks since, complaints about food shortages and reports of patients being denied medical care have shocked the nation.On January 2, Yuzhou, home to 1.2 million people, was placed under lockdown after it reported three asymptomatic cases.Yuzhou recorded 74 symptomatic local cases on Monday, the largest current outbreak in the country, according to the NHC. Meanwhile, 29 residential communities in Tianjin city are under lockdown after Omicron was detected in at least two residents Saturday — China’s first reported community spread of the highly transmittable variant. Tianjin reported 21 infections on Monday — 11 symptomatic and 10 asymptomatic — bringing the total of its current outbreak to 53.The city of 14 million is located just 130 kilometers (80 miles) southeast of Beijing, where the Winter Olympics are due to begin February 4. Zero-Covid strategy: China is one of the only places in the world still aiming to eliminate Covid-19 within its borders.But the frustrations of locked down residents underscore the growing challenge facing its zero-Covid policy, which relies on a playbook of mass testing, extensive quarantines and snap lockdowns to stamp out any resurgence of the virus.