You drop a piece of cucumber on the floor. Do you immediately throw it in the bin or reassure yourself of the age-old “five-second rule” and reckon it’s fine to pop it in your mouth after a quick rinse?
If you fall into the latter camp, John Tregoning, professor of vaccine immunology at Imperial College London, has some bad news. He refers to three studies into bacteria transfer that all point towards the rule being false.
