The number of new daily coronavirus cases in the North of England is increasing, scientists have warned.
While the rate of new COVID-19 cases remains flat across the UK, it has risen slightly in the North, they say.
The news follows a number of recent coronavirus outbreaks across the UK.
Areas of Lancashire, West Yorkshire and Manchester have all seen increases, according to the COVID Symptom Study app figures.
The tracker is a collaboration between King’s College London, Guy’s and St Thomas’ hospitals and the health science company Zoe.
It found there were, on average, 1,884 daily new cases of COVID-19 in the UK over the two weeks up to 18 July, excluding care homes.
Its latest figures are based on information from 13,451 swab tests carried out between 5 July and 18 July.
Researchers say the numbers show a north/south divide in England.
While cases in the South of England have largely stayed the same, with little or no difference from the previous week, a number of areas in the North have experienced increases.
There were increases in Blackburn with Darwen in Lancashire, Kirklees in West Yorkshire and Salford, Greater Manchester.
The highest prevalence in the UK is in Blackburn with Darwen, where 0.40% of the population is symptomatic with COVID-19, according to the app, which has 1,016 users in that region.
Most of the regions on the COVID Symptom Study’s new “watch list”, featuring the areas with the highest estimates of coronavirus cases, are in the North of England.
Overall, the app estimates that 28,048 people have symptomatic coronavirus in the UK.
Those behind the app said its data the past week revealed that COVID-19 symptoms and outcomes worsen in colder, less humid weather.
“We are now starting to see the figures in the North creep up week on week,” said Tim Spector, professor of genetic epidemiology at King's College London.
“The numbers are still very small so we can’t say with 100% certainty that COVID is increasing significantly but it does make us focus on those areas.
“To understand if these increases are significant or not, we need as many people as possible in these areas to be logging in the app.
“So we are calling for people living in the North, to download the app and get logging, as without them, it will make spotting any real hotspots accurately much harder.
“Our data suggests that levels have bottomed out at around 2000 cases per day which is too many, so we all need to be conscious of the dangers and to continue to practice high levels of personal hygiene, wear a face mask, social distance and know all the signs of early disease.”
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