Credit: Crown Copyright/Open Government Licence v3.0

After a precipitous decline in the late summer, the month of October saw a steady increase in the weekly number of exposure notifications issued by the NHS Covid-19 app.

As venues began reopening in May and June – while still subject to restrictions – the number of weekly alerts issued by the contact-tracing program shot up from fewer than 50,000 to almost 700,000.

But, as soon as restrictions were removed in July, this figure plummeted; the first full week after all remaining measures were lifted, the notifications received across England dropped by almost half to below 400,000 and, within a month, the total had fallen to less than 250,000.

After continuing to decline from there, the number bottomed out during the first week of October at 117,982.

In the three sets of weekly figures published since then, the volume of alerts has rise each time, despite cases beginning to level out.

Related content

• NHS Covid app: venue check-ins fall off a cliff as contact alerts continue to decline
• Covid app updated to reduce isolation alerts
• NHS Covid app: from 16 August exposure alerts will ask users if they have been fully vaccinated

In the seven days to 13 October, 132,438 contact-tracing alerts were sent; a total of 257,196 people through England tested positive for coronavirus during the same period. 

The most recent data, for the week ending 27 October, shows a 49% rise in notifications compared with a fortnight prior, with 197,322 sent. The number of cases was more or less flat, at 260,452.

In the week of 13 October, 0.5 alerts were issued for every positive test; in the week of the 27, the figure was 0.76.

Although the number of weekly alerts is still a long way off its summer peak, the rise in the last month suggests usage of the app is steady – or even rising slightly, after months of decline. The technology has been downloaded 28.6 million times but, even near the height of its usage, government data suggested that millions of people had not enabled core functionality. 

In April – when the app had been downloaded a cumulative total of 23.3 million times – government data reported that only 16 million users “had the app fully or partially enabled on their phone”. And even this reduced number included “users who have opted to disable contact tracing”.

By 4 August, just two weeks after the final lifting of restrictions, the message from leaders of key government health agencies was that “it is not possible to make a reliable and consistent calculation of the number of people with the app enabled at any one time”.