WhatsApp is for old people. At least that’s what my first-year medical students tell me. Young people, especially teenagers, communicate through Snapchat, an app that reaches 90% of 13-to 24-year-olds and 75% of 13-to 34-year-olds across the UK. It has more than 21 million active users in Britain per month, which is almost one-third of the population, and each accesses the app on average more than 50 times a day.
If we
