Influenza (flu) is a common viral infection that comes in 'seasons' (winter in the UK). Flu can cause more severe symptoms than the common cold. Some people can become seriously ill with flu, needing hospital treatment, and can sometimes be life-threatening. Certain groups of people, such as older adults and young children, are at higher risk from flu infection.
This is a companion discussion topic for the original article at https://patient.info/infections/influenza-and-flu-like-illness/immunisation-for-flu