The annual influenza campaign is one of the United Kingdom’s most successfully implemented public health programmes—uptake in those over 70 is estimated at 78%, the highest in Europe.1 The rationale for the programme is based on the knowledge that the vaccine is effective and cost effective. Although age related deterioration of immune function makes vaccines less effective in older people than in younger ones, the one available good quality randomised controlled trial shows good overall vaccine efficacy for serologically confirmed influenza (58%, 95% confidence interval 26% to 77%) and clinical influenza (47%, 27% to 61%) in those over 60.2

Large observational studies from the United States have also provided evidence for benefits against less influenza specific outcomes. These studies found that in the over 65s the vaccine reduces hospital admissions for pneumonia and influenza by 27% and all cause mortality by 48%.3 However, in the past few years, some researchers have questioned the plausibility of these less specific findings,4 5 6 and several prominent media articles have suggested that the vaccination programme is not worthwhile.

So what does the evidence to date say? A systematic review published in 2005 …