Seasonal influenza and vaccination coverage

Seasonal influenza represents a considerable public health burden, and annual vaccination represents the most effective preventive strategy for amelioration of this problem. Certain groups are at greatest risk, such as the young, the elderly, pregnant women, and those with chronic underlying medical conditions: the high-risk groups. Traditionally, annual vaccination has been targeted to people classified as being at high risk, particularly the elderly, but in recent years, there has been a broadening of vaccination recommendations to target larger numbers of people. This has recently culminated in the recommendation of "universal vaccination" in the USA (everyone over 6 months of age is recommended to receive the seasonal influenza vaccine). In this review, we will look at coverage rates in Europe and the USA, changes in vaccination guidelines, and the rationale for broadening vaccination recommendations. It is clear that often only modest improvements in vaccination coverage have occurred recently, with programs targeting risk groups, but some substantial increases in coverage have followed the broadening of USA vaccination recommendations to all persons under 18 years and to middle-aged healthy adults (> or =50 years). It is likely, however, that some of these increases may be because of the increased awareness related to the recent pandemic. It is unclear if increases in coverage will translate into public health benefits, but perhaps results will be similar to experiments with universal vaccination in Ontario, Canada, where increased coverage may have provided some reductions in healthcare use, fewer influenza-associated deaths, and even financial benefits.