Scientists have predicted that the next flu pandemic to hit the UK could kill as many as 886,000 people and infect 43 million — about three-quarters of the entire population.

Data for the study was collected using a mobile app — downloaded by around 29,000 people by the end of the experiment — which tracked their interactions with others for eight months.

Two researchers — mathematician Hannah Fry and medic Dr Javid Abdelmoneim — analysed data from the app and calculated how quickly the next flu strain would spread around the country.

Fry acted as patient zero, the first person to be affected. By tracking her movements and others researchers calculated how quickly the virus could spread from the Surrey town of Haslemere, which has some 17,000 inhabitants.

Three months after the beginning of the experiment, they calculated that the virus would have reached Edinburgh and Northern Ireland.

According to Mail Online researchers found 86% of the 500 users in Haslemere who downloaded the app had become infected within three days.

Teachers and shopkeepers were found to act as so-called super spreaders, infecting more than others due to their jobs.

The study went on to find that vaccinating these super spreaders would cut the outbreak by a fifth.

The outcome of the study — undertaken as part of a BBC TV show — shows the danger that a mutated influenza pandemic could have on a country’s population and confirms previous predictions by government officials, who described a potential new flu strain as a bigger threat to humanity than terrorism.

This isn’t the first time apps and technology have been used to try to understand how diseases spread.

In 2011 a mobile phone app called FluPhone was developed by researchers at the University of Cambridge Computer Laboratory.

But as technology improves and people use their phones more often it’s thought contagion modelling will become more accurate.

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The latest experiment comes around a century after the Spanish flu broke in Europe, killing 50 million people and claiming three times as many lives as World War I.

Concerns about a new influenza strain has spread across the UK and US over recent weeks due to the cold weather snaps.

This led the Cabinet Office to rank a pandemic influenza as the first and biggest threat in the UK’s Risk Register ahead of terrorism and cyber-attacks.

Tedros Adhanom, chief of the World Health Organisation, warned last month that humanity is “vulnerable” to a pandemic.

According to the researchers, the next UK flu strain is likely to come from South-east Asia, giving health officials a four-week warning.

NHS figures show that this winter’s outbreak, which was mainly caused by the Japanese and Aussie flu, claimed at least 271 lives in the UK.

Chris Chiu, senior lecturer in infectious diseases at Imperial College London, told the Mail Online that the next pandemic could come from animals.

Flu exists in animals such as birds or pigs, and from time to time you’ll get these other animal flus that cross over into humans.

The vast majority of people won’t have any immunity against that new strain of flu, so it spreads very quickly across the world.

We know that a pandemic will come, there’s no doubt about that, these are regular occurrences.

What we saw with the last flu pandemic from 2009 is that our health service was almost unable to cope.