Excess Mortality Associated with Influenza in England and Wales

An estimate was made of the number of deaths and the number of new sickness benefit claims associated with influenza outbreaks in England and Wales for the winters of 1968–1975. The method involved analysis by stepwise regression of the relationship between notified mortality and new sickness benefit claims and a number of variables thought likely to Influence these notifications. The variables included the Incidence of clinical influenza as recorded by the Royal College of General Practitioners; the time interval since antigenic shift and drift in the influenza virus; the number of virus Isolations reported by the Public Health Laboratory Service; the time trend; mortality In the previous year; and winter temperature. The estimates obtained, together with their standard errors, indicated that both mortality and morbidity in the working age population due to influenza can be estimated within reasonable limits. It was possible to make a good óstlmate of the number of deaths to be expected in any winter and, by setting to new values those variables associated specifically with the occurrence of influenza, of the number of deaths to be expected In its absence. Excess mortality associated with Influenza was found to be considerable even In the absence of major epidemics. About 65 per cent of this excess mortality was in the elderly population, but no evidence was obtained In these epidemics of an excess In children under one year of age.