Tens of millions of Chinese confined at home, schools closed, businesses in limbo and whole cities at a standstill. Once again, China is locking down enormous parts of society, trying to completely eradicate Covid in a campaign that grows more anomalous by the day as the rest of the world learns to live with the coronavirus.

But even as the costs of China’s zero-Covid strategy are mounting, Beijing faces a stark reality: It has backed itself into a corner. Three years of its uncompromising, heavy-handed approach of imposing lockdowns, quarantines and mass testing to isolate infections have left it little room, at least in the short term, to change course.

China’s leader, Xi Jinping, has made clear that zero Covid is as much an ideological undertaking as a public health one. He has tied support for the policy to support for the Communist Party, and hailed its execution as proof of China’s edge over Western democracies. He has prioritized nationalism over the guidance of scientists. Any reversal, or adjustment, would seem to undercut his vision, especially ahead of a major Communist Party meeting next month where Mr. Xi is all but assured to extend his rule.

The emphasis on politics has created practical problems. Beijing has refused to approve foreign vaccines, opting instead to provide only less effective homegrown ones to its 1.4 billion people. The government has pushed propaganda depicting the virus as having devastated Western countries, feeding widespread stigma and a fear of infections even among the young and healthy. It has silenced voices seeking to offer a different approach, labeling them traitors.

Buoyed by its early success at containment, the party was slow at first to encourage vaccination, leaving many older Chinese vulnerable. Since few Chinese have natural immunity from the virus, the risks of loosening controls are potentially even higher.

“That sort of makes the zero-Covid policy self-sustaining,” said Yanzhong Huang, a senior fellow for global health at the Council on Foreign Relations.

At least 65 million Chinese are currently under some form of lockdown, according to a tally by Chinese media, including the southwestern city of Chengdu, home to 21 million people. In cities that are not battling outbreaks, quashing Covid still dictates the rhythms of daily life. Residents line up for mandatory, regular testing and obsessively monitor their health codes, digital markers that dictate whether they can move freely.

Many Chinese have found ways to cope, even if reluctantly: putting in longer hours to scrape up more money, cutting back on spending. Complaints about a shortage of medical care or food often emerge, but some residents say they support the overarching goal.

Who can get used to this?” said Zhang Lang, a grocery store owner in the southwestern city of Guiyang, who has been under lockdown for three days. “But there’s no choice,” he said. “The epidemic is coming. Do you want what happened in America to happen here?”