Travellers should stick to mobile data or download vaccine information before they travel 2 May 2021 • 6:00am Britons travelling abroad have been warned against using airport WiFi to log into the NHS app to their vaccine passports in case they hand over their health details to hackers. It follows Government plans to add vaccine passports to the NHS smartphone app which could be used to allow people to travel abroad by proving they have been vaccinated against coronavirus. But logging into the app and loading health data while on unsecure WiFi networks could see hackers gain access to passwords as well as sensitive personal information about people’s health conditions.