Vaccination of high-risk patients against influenza: impact on primary care contact rates during epidemics. Analysis of routinely collected data.

A general practice (GP) based retrospective cohort study was conducted to assess the effects of influenza vaccination on the primary care contact rate during influenza epidemics. Given the rising workload of family physicians, particularly due to ageing of the population, it is very relevant to know to whether influenza vaccination of high-risk patients reduces the contact rate during epidemics. No effect of vaccination was found on the contact rate of GP during a mild epidemic period. During a 'normal' influenza epidemic, the workload was reduced through fewer contacts by patients with cardiovascular or diabetic diseases. Epidemic periods severe enough to show contact rate reduction occurred approximately every other year.