In late March, as Shanghai residents began to worry that rising coronavirus infections would lead the city into its first mass lockdown, authorities turned to social media to calm the situation.

“Please do not believe or spread rumors,” the city government wrote on China’s Weibo platform on March 23, where posts warning that people would imminently be confined to their homes had already spurred panic buying of food.

Just days later, the outline of the rumours — if not the fine details — turned out to be true. In response to thousands of cases, China’s largest city last Sunday unveiled the most significant lockdown measures in the country since the sealing off of Wuhan when Covid-19 first emerged more than two years ago.

The lockdown of its leading financial centre — which initially cut Shanghai in two before eventually confining everyone to their homes by the weekend — was a startling refutation of any sense that China was beginning to relax its approach to the virus. President Xi Jinping in mid-March emphasised the need to minimise the impact of the pandemic on the economy. His comments had been interpreted by some as a signal that Beijing was preparing to ease up on its hardline zero-Covid policy.

Instead, the measures introduced in Shanghai on March 28 highlighted the government’s commitment to a now-globally unique strategy — fine-tuned across outbreaks from Xi’an to Shenzhen — of attempting to completely eliminate local cases no matter the economic and social costs.

Until recently, Xi could tell his own citizens — and the rest of the world — that

China had successfully kept the virus at bay. But two years of political investment in the zero-Covid approach is now under more pressure than ever as the country records thousands of daily cases despite an escalating wave of restrictions — even if almost no deaths are being officially reported.