How to protect yourself from the superflu, according to a virologist

At medical school, the professor who taught me about flu shared what he regarded as the gold standard way to diagnose a case of the virus: the £20 note test. The basic premise was that, if someone said they had put a £20 note on the garden gate and it’s yours for the taking but you have to go and get it, a person with a real dose of flu would always forgo the reward in favour of staying in bed.