Fall in Covid-19 symptoms on tracker app suggests lockdown is working

In the course of a few weeks we have gone from a “containment” strategy where an attempt was made to trace all Covid-19 cases to “mitigation” and then “suppression” . The containment phase was the only one with wide scale testing but it didn’t last long. In subsequent phases individuals exhibiting symptoms were told to self isolate.

As Owl understands it, in these phases, neither GPs nor NHS 111 (if you could get through) took any records of who thought they may have the virus. There are two obvious consequences: there is no one checking on patients to advise them, as Boris Johnson was, when to go to hospital (deterioration can be very rapid); and we haven’t a clue on how many people exhibited symptoms. 

Owl has more than a sneaking suspicion that resource constraints played a large part in what otherwise seems an inexplicable decision (not enough testing kits and not enough NHS 111 staff). Confused chains of command may also have contributed. It doesn’t look very well organised, remembering we had a two week start over most of Europe.

The Covid-19 tracker app tries to fill this vacuum. Here are more results.

(The tracker app is now being rolled out in the USA, another country that desperately needs data on the Covid-19 transmission.) 


Researchers at King’s College London said there had been a drop in people reporting symptoms since April 1.

Researchers believe that the coronavirus lockdown is working as data from a tracker app suggests that the number of people aged 20-69 who are reporting Covid-19 symptoms has fallen from 1.9 million to 1.4 million across the UK.

The drop, by around 500,000 people since April 1, is indicated in analysis of data from the Covid Symptom Tracker app, which is used by more than two million people.

Contributors can track their daily health on the specially created app, which is also being used by healthcare and hospital workers nationwide.

The researchers behind the app, which was developed by a team at King’s College London, said their latest figures suggest that staying home is having a big impact on the spread of the virus in the UK.

Even though hospital admissions and deaths are still on the rise, we hope that these figures offer a much needed light at the end of the tunnel

Prof Tim Spector

They say the drop in new symptoms indicates that although the number of hospital admissions and deaths from Covid-19 are currently rising, they should start to fall in about two weeks’ time provided social distancing continues.

The team believes the two-week lag is caused by the delay between symptoms starting and becoming very severe.

Lead researcher, Professor Tim Spector from King’s College London, said: “It is really encouraging to see that the rate of new symptoms being reported is beginning to fall.

“Even though hospital admissions and deaths are still on the rise, we hope that these figures offer a much needed light at the end of the tunnel.

“We have been totally blown away by the public’s response to the app.

“On the first day we saw one million members of the public download it making it one of the most successful first days for an app ever, and already probably the UK’s largest citizen science project.

“The altruism of the UK public combined with modern technology is allowing us to rapidly collect huge amounts of invaluable data to help us better understand this deadly virus.”

Researchers say that their data concurs with what has been reported by NHS Digital, based on much smaller numbers.

This shows a decline in the number of calls to NHS 111 by people with Covid-19 symptoms since March 22.

While symptoms have been decreasing nationally, researchers say that their data shows that in all areas there are still many people with active symptoms.

The data also shows that individual areas vary.

Most of the country’s larger cities like London, Birmingham, Glasgow, and Liverpool continue to have very high levels of symptoms in the community, even this far into lockdown. South Wales is another hotspot.

There are significantly higher levels of symptoms across the Midlands, the North of England and southern Scotland than in the south-west of England.

The Covid Symptom Tracker app was developed by a King’s College London team in association with the Guy’s and St Thomas’ NHS Foundation Trust, NIHR Biomedical Research Centre and healthcare start-up ZOE Global Limited.

To download the app, and to view an interactive map showing the suggested distribution of Covid-19 in your area, see covid.joinzoe.com


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