The number of alerts sent to users of the NHS COVID-19 app in England and Wales has fallen by 20%.

A total of 317,132 alerts were sent to users in the week to 4 August telling them they had been in close contact with someone who had tested positive for coronavirus – a drop of just under 80,000 – government figures show.

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A total of 395,971 alerts were issued in the previous week.

It comes after the NHS COVID-19 app was updated last Monday to ensure fewer contacts of people with coronavirus are told to isolate.

The app now only looks back at contacts two days before someone tests positive, compared with the five days being tracked before.

From Monday 16 August, people who are fully vaccinated will no longer have to isolate when identified as a close contact of someone who has COVID-19 – but there have been calls for this change to be brought forward.

The new rules will apply to people who had their second vaccine dose at least 14 days before coming into contact with a positive case.

COVID app users who are identified as close contacts of someone with coronavirus will be asked to self-declare if they are double-jabbed or under 18 and will be advised to book a PCR test.

There are additional precautions for health and social care staff, who will have to provide a negative PCR test before they can go back to work.

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They will also need to take daily lateral flow tests for 10 days, while those working with clinically extremely vulnerable patients will have to undergo a risk assessment before returning to work.

Health Secretary Sajid Javid hailed the upcoming changes.

He said: “Getting two doses of a vaccine has tipped the odds in our favour and allowed us to safely reclaim our lost freedoms, and from Monday we can take another huge step back towards our normal lives by removing self-isolation requirements for double-jabbed people who are contacts of people with COVID-19.”

The government said people will continue to be encouraged to do rapid lateral flow testing twice a week to help find asymptomatic coronavirus cases.