Influenza, commonly known as flu is a viral infection that attacks the respiratory system i.e. the nose, throat and the lungs. It is highly contagious, meaning it can spread easily from person to person. It can rapidly transmit in crowded areas including schools and nursing homes.

Symptoms usually start with a cough or a sneeze, resulting in the spread of tiny droplets containing the virus which can be breathed in by others, or it can land on surfaces that are touched. Even people with mild or no symptoms can infect others.