While adolescent mortality has declined by more than a quarter over the past two decades, comprehensive analysis of global data calculated that in five years, at least half of the world’s 10- to 24-year-olds will be living in countries where preventable health problems such as HIV/Aids, early pregnancy, depression and poor nutrition pose a “daily threat to their health, wellbeing and life chance”. Young people’s health has reached a “tipping point”, the authors warned.