Do you know what the Government considers to be the biggest risk to life in the UK?

It’s not terrorism or war; it’s flu. In the past century there have been four pandemics, the worst of them in 1918 when the Spanish flu killed 100 million people worldwide. In this one-off documentary we meet the experts working to prevent and manage the next big outbreak.

Dr Hannah Fry spearheads an experiment to simulate a deadly virus, using app technology to ‘infect’ and track volunteer users to see how far they travel and how many people they come into contact with.

The results are astonishing and will help scientists predict how disease spreads and what can be done about it.