Researchers from King's College London, who helped design the app, said the figures have dropped from two million to 582,640 from the beginning of April, but warned that now was "definitely not the time for complacency".
They said predictions from the data were based on 871,458 participants who logged symptoms consistently for seven days.
The data suggests there are still a large number of infectious people in the UK and that there is now no clear difference between cities and the countryside when it comes to predicted cases of the virus.
Lead researcher Professor Tim Spector said there had been concerns that user participation would dip over time, but he had been "blown away" by the continuing response from the public.
"It's fair to say that when we launched the app, we were unsure how many people would download it and also how long people would keep contributing to it," he said.
"However, with 2.4 million downloads and over 800,000 logging daily, the reaction from the British public has definitely surpassed all of our expectations. It's been truly inspiring to see."
Prof Spector added that it was "very reassuring" to see the number of predicted cases continuing to fall day on day.
"But with deaths still high, this is definitely not the time for complacency," he said.
"We believe our population's symptoms are changing around two weeks before most people are admitted to hospital.
"The data from the app is giving us insight into just how common the virus is and how differently it affects people. We are learning something new each day."
Other scientists said the data continues to "strongly support" the positive effects of the UK lockdown, which is expected to be extended for a further three weeks.
Professor Keith Neal, emeritus professor in the epidemiology of infectious diseases at the University of Nottingham, said: "This Covid tracker app is looking for symptoms that might be Covid-19.
"Under half of patients tested for Covid-19 are found to be positive and the symptoms they report can have many causes.
"A fall in these symptoms strongly supports the benefits of lockdown as this will interfere with the transmission of all respiratory pathogens as there are less person-to-person contacts.
"The tool is useful as it is simple to use and data is produced in a timely manner and the accuracy should improve with the warmer weather as other respiratory viruses decline in the warmer weather."
Contributors can track their daily health on the specially created app, which is also being used by healthcare and hospital workers nationwide.
First and foremost - and rarely have I written down these words with more sincerity - I hope this finds you well.
Almost certainly you are here because you value the quality and the integrity of the journalism produced by The Yorkshire Post’s journalists - almost all of which live alongside you in Yorkshire, spending the wages they earn with Yorkshire businesses - who last year took this title to the industry watchdog’s Most Trusted Newspaper in Britain accolade.
And that is why I must make an urgent request of you: as advertising revenue declines, your support becomes evermore crucial to the maintenance of the journalistic standards expected of The Yorkshire Post. If you can, safely, please buy a paper or take up a subscription. We want to continue to make you proud of Yorkshire’s National Newspaper but we are going to need your help.
Postal subscription copies can be ordered by calling 0330 4030066 or by emailing [email protected]. Vouchers, to be exchanged at retail sales outlets - our newsagents need you, too - can be subscribed to by contacting subscriptions on 0330 1235950 or by visiting www.localsubsplus.co.uk where you should select The Yorkshire Post from the list of titles available.
If you want to help right now, download our tablet app from the App / Play Stores. Every contribution you make helps to provide this county with the best regional journalism in the country.
Sincerely. Thank you.