Half of Beijing’s districts reported new coronavirus cases on Monday in the country’s most serious upsurge in infections for months. Authorities announced that 79 people had been hospitalised and there were 36 new infections in the Chinese capital, a day after more than 75,000 tests were conducted in the city of 20m. The cluster of infections linked to Beijing’s largest seafood and vegetable market has become the most serious outbreak since China said it had largely succeeded in controlling the pandemic.

Life in Beijing had mostly returned to normal after more than 50 days without a confirmed case. But on Sunday, districts began to reimpose measures to control the movement of people. Restaurants and other businesses were again required to collect personal information of customers, only a week after such measures were relaxed.

The outbreak in Beijing was a shock to the Chinese government, and we believe the risk of a second wave in China rose significantly over the past weekend

Ting Lu,chief China economist at Nomura

The market at the centre of the outbreak has been closed and several residential compounds have been locked down. In the months following the start of the outbreak in Wuhan, Beijing became one of the most difficult places in China to enter. All travellers to the city were required to quarantine for 14 days. Those restrictions were eased in May.

The new cases threaten to deliver a blow to the Communist party’s attempt to revive economic growth after output fell to its lowest level in a generation. “The outbreak in Beijing was a shock to the Chinese government , and we believe the risk of a second wave in China rose significantly over the past weekend,” said Ting Lu, chief China economist at Nomura.

Many indicators of economic growth have shown positive signs in recent weeks. The National Bureau of Statistics said on Monday that industrial production in May rose 4-4 per cent year on year, higher than the previous month but still below some analysts’ expectations.

Fixed-asset investment for the first five months of the  year fell 6.3 per cent from a year earlier, a sign that investments in  real estate and infrastructure were still suffering in the wake of the crisis. Growth in retail sales was down 2.8 per cent.