Surveillance of influenza-like illness in England and Wales during 1966-2006.

We report surveillance data collected since 1966 from a general practice database in England and Wales. Incidence rates of influenza-like illness (ILI) peaked during the winter of 1969/70, and were then followed by a decade of heightened activity. There has since been a gradual downward trend of ILI, interspersed with winters of heightened activity; since 1999/2000, the incidence of ILI has been at its lowest for 40 years. We argue that the decade following the herald waves of the pandemic could be equally important for the planning of healthcare services in the community.