Influenza is an acute, highly infectious viral infection. Seasonal outbreaks occur annually across the world, presenting a major public health challenge. Older people and those with chronic conditions are most at risk and for these groups secondary infection and complications can be severe. Implementing infection prevention and control measures is not straightforward because of the types of settings where many older people receive care, the special needs of frail older people likely to be most seriously affected, and because little is known about the mode of transmission of the virus.