Covid Symptom Tracker is in fact the third-most popular app in Apple's UK store and it's also currently second in Google Play's new releases chart.
The creators of the app hope to help the British public to distinguish between the common cold and coronavirus symptoms.
Speaking about the app's development, Professor Tim Spector - a genetic epidemiologist at King's College who has specialised in the genetics and medical histories of twins - told BBC News: "I was rather depressed as they were shutting down everything in the university and I thought that twins are the best studied people in the country, so how can we use that information in this crisis?"
Developers of the app are targeting one million downloads in 24 hours, and Professor Spector eventually hopes to pass the data on to the NHS in the UK.
He said: "The NHS hasn't come up with a better alternative and this app seems to be working.
"We are hoping to get to one million downloads by the end of the day and we will also be ready to release data by then for the NHS, data modellers and researchers to play with."