Businesses are a warning of ping chaos caused by an upsurge in the number of coronavirus infections being registered by the NHS test and trace app.

More than 520,000 alerts were sent to users of the NHS Covid-19 app in England and Wales in the week to 7 July, up 46% on the week before, saying they had been in close contact with someone with the virus.

Anyone ‘pinged’ by the app is advised but not compelled to self-isolate for ten days to reduce the risk of spreading the virus.

BMW-owned Rolls Royce today said it might have to slow production at its factory in Goodwood if many more staff began self-isolating.

Though not yet critical, the luxury carmaker said it would reduce its shifts from two to one if the situation got worse.

Unite said NHS Test and Trace app pings had left swathes of factories critically short of staff, especially in the car sector.

As well as Rolls-Royce, 10% of Nissan’s Sunderland car plant workplace had been pinged and told to isolate, it said.

There was a risk people would stop using it if it becomes a nuisance, the union told the BBC, potentially leading to potential public health consequences,

In a radio interview, Communities Secretary Robert Jenrick said people needed to take the app seriously, but  the government would give “further thought to how we can ensure it is a proportionate response.”