Observations on the influenza epidemic of November/December 1989.

This paper reports on the surveillance of influenza by the weekly returns service of the Royal College of General Practitioners during the epidemic of November/December 1989. An epidemic of influenza became evident in mid-November and incidence peaked in the week beginning 6 December. The increase in incidence of influenza-like illness and of aggregated data for all respiratory disease to above the levels for non-epidemic years occurred one week before that attributed to influenza. The pattern of incidence was similar in the three geographic regions of England and Wales. The peak was first achieved in the age group 5-14 years and last in age 65+ years. The pattern of deaths from all causes closely followed the pattern of respiratory disease with an interval of between one and two weeks. During the period 15 November to the end of the year there were approximately twice as many people reporting respiratory disease than was usual for this time of year. The peak weekly incidence was the highest recorded for 12 years but it was substantially less than the peaks for the winters of 1969/70, 1972/73 and 1975/76. Further research is in progress to establish the most effective means of monitoring influenza epidemics.