Sarah Newey Thu, June 11, 2026 at 4:24 PM UTC 4 min read Add Yahoo as a preferred source to see more of our stories on Google. A pandemic caused by a respiratory virus – such as avian influenza – is the UK Health Security Agency's worst fear - The Image Bank RF It all starts very quickly. Before health officials have any chance to contain a new strain of influenza, the highly contagious virus has landed in Britain and taken hold.