The daily tally of local Covid infections continued to edge down in Shanghai on Wednesday, as the city reported just under 5,000 cases – around 600 fewer than the previous day.

Of the new infections, 4,722 were asymptomatic, while 260 were symptomatic.

Shanghai authorities reported 16 Covid-related deaths, down from 20 a day earlier.

Zhao Dandan, deputy head of the city's health commission, said the patients – at an average age of 83 – all had underlying illnesses.

He said control measures and screening tests are proving effective as more people come out of lockdowns.

The official said as business production resumes in the city, closed-loop staff management is required in factories, construction sites and commerce companies to prevent virus transmission.

"Workers of different shifts are to have no contacts and they should avoid going out to prevent cross-infection," Zhao told a press briefing.

"There should be staggered meal times. Workers should not congregate or have meals together."

Meanwhile, the number of cases in Beijing dropped slightly, with 46 symptomatic infections and five asymptomatic cases.

The capital's health commission said all the new patients had been hospitalised and epidemiological investigations were ongoing.