Epidemic and pandemic diseases are among the greatest of all threats to human health and security, even though its risks remain widely underestimated and the world’s preparedness and capacity to respond is woefully insufficient. After more than 11,000 deaths caused by the Ebola epidemic, major outbreaks of Middle East Respiratory Syndrome and the pandemics of H1N1 and H5N1 influenza, the Zika virus now brings grave concern in an increasingly globalised and connected world that makes disease transmission across borders a very dangerous reality. The UN believes the World Health Organisation should be the single global health leader in tackling these issues, but what measures should it prioritise and what role should other stakeholders take to help?