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CNN  — 

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.

Zhu Xiaqing, the nurse who took the video at the quarantine hospital, told the local Fujian Health Daily newspaper her eyes were wet with tears when she saw an ambulance full of children arriving, all sealed up in hazmat suits. They had arrived late because a child didn’t want to leave home and was crying for two hours before being coaxed into the ambulance, she said.

Upon arrival, the children had CT scans by themselves. Some were so young they couldn’t climb onto the scanning table and had to be picked up by a doctor, Zhu said.

“Seeing little children all alone by themselves, without parents by their sides, in a hospital (they are) unfamiliar and scared of – at that moment my heart really ached,” she added.

On Weibo, some users questioned why children this young couldn’t be accompanied by their parents. Others pointed out their parents were likely put in centralized quarantine in other facilities as close contacts of the infected.

“It’s basically a strategy of ‘rather killing a thousand by mistake than letting one go,’” said Jin Dongyan, a virologist at the University of Hong Kong. “Children shouldn’t have needed to undergo such extreme quarantine measures. This is the social cost of the zero-tolerance approach.”

Government workers stop a biker at the entrance to a residential block under lockdown in Xiamen in southeast China's Fujian province on September 14.

The strict – and often hectic – implementation of containment measures has sparked discontent before. In June, hundreds of residents in Foshan, Guangdong province, protested against weeks of prolonged lockdowns on their neighborhoods. Footage of the rally was swiftly scrubbed from the internet, while on social media, those who criticized or questioned the zero-Covid policy were attacked and muffled by online nationalists.

The zero-Covid strategy still enjoys broad support among the wider Chinese public, many of whom have grown accustomed to the benefits associated with Covid-free living and remain fearful of the virus – partly due to unrelenting state media coverage on the devastation the pandemic has caused abroad.

“The success of the stringent approach is partly built on public fear. This is not ideal,” Jin said. “The correct way is to tell the public the truth (about the need to coexist with the virus), which is the only sustainable way going forward.”

Across the world, a growing list of countries have opened up after mass vaccinations. Others, such as