President Xi Jinping faces a critical test of his zero Covid strategy this week as Shanghai attempts to rein in an outbreak of largely asymptomatic cases without resorting to the draconian lockdowns routinely employed across the rest of China.

Chinese health authorities reported on Sunday that 5,702 new cases had been discovered the previous day, about 80 per cent of them asymptomatic. Shanghai, with a population of 26mn, reported 2,631 asymptomatic cases, accounting for about 60 per cent of China’s asymptomatic total.

In their effort to control the outbreak, Shanghai officials have tried to implement targeted lockdowns of relatively small districts while also urging residents to self-diagnose with recently approved rapid antigen tests.

A member of Shanghai’s Covid task force said on Saturday that calls for a relatively brief citywide lockdown of three to seven days were misguided because of the “important role [we play] in national economic and social development”.

“If the city came to a complete stop, there would be a lot of international cargo floating on the East China Sea, which would have a big impact on the national and global economy,” Wu Fan said at a briefing.

Xi’s zero Covid strategy has so far failed only in one city — Hong Kong, which recently backed down from plans to conduct mass tests of its 7.4mn residents and isolate all positive cases in newly built quarantine facilities.

The semi-autonomous territory has been overwhelmed by its current outbreak, which accounts for the vast majority of its 1.1mn Covid cases and almost 7,000 related deaths since the pandemic first erupted in central China in January 2020.

According to a recent study of the Hong Kong surge, the fatality rate for Covid patients aged 80 or older who had received two or three shots of a Chinese vaccine was three per cent.

That implies a potentially large death toll if the rest of China, with about 27mn people aged 80 or older, were also to lose control of Covid, especially in poorer provinces and rural areas that have far more rudimentary healthcare systems than Hong Kong’s.

While Xi has recently said that China should minimise disruptions to the economy to “pay the lowest price” while pursuing zero Covid, his administration has refused to alter course fundamentally. As a result, the world’s most populous country has been effectively sealed off from the rest of the world for more than two years.

All international arrivals are subject to punishing three or four-week quarantines and visa issuance to foreigners other than diplomats has come to a near halt.

In terms of symptomatic cases, mainland China’s worst outbreak is still unfolding in the northeastern province of Jilin, population 24.1mn, which has implemented much tougher lockdown measures than Shanghai. Jilin accounted for almost 90 per cent of the 1,250 symptomatic cases reported by China on March 26.