Covered from head to toe in a white hazmat suit, a small child carrying a backpack half the size of his body toddles down a hospital corridor and arrives at a CT scan room — all by himself.

“A 4-year-old boy has been infected (with Covid-19), unfortunately,” a caption in the video reads. “No accompanying parents. Going to quarantine alone.” The scene, captured by a nurse at a quarantine hospital in the city of Putian, the epicenter of China’s latest Delta variant outbreak, gripped millions of people when it went viral on Chinese social media this week. “It makes my heart ache,” said one of the top comments on Weibo, China’s Twitter-like platform. “My eyes are getting teary,” said another.

The video serves as a poignant reminder of the human cost of China’s prized zero-Covid policy, which has helped the country quell multiple resurgences of the virus. The elimination playbook consists of placing entire neighborhoods under lockdown, testing millions of residents in a matter of days, and swiftly isolating infected people and their close contacts in designated facilities. This time, the strict measures were applied to schoolchildren — among whom the outbreak was first detected and spread quickly. In Putian, 57 of its recently reported 129 cases are under the age of 12, according to the government. To prevent further transmission, infected children as young as kindergarten age are separated from their parents and put in hospital isolation.

In a news conference Thursday, the Putian government said China’s epidemic control rules bar Covid patients from any company during isolation and treatment. But if a child and their parent are both infected, the hospital would try to arrange them to stay in the same ward, an official said. Initially, some children who came into contact with the infected but tested negative were also quarantined away from their parents. That policy was later relaxed, with children under 14 allowed to stay with their parents or other family members in quarantine — but isolation for infected children remains.