Influenza vaccination and the end of simplicity.

Influenza is a major, persistent health problem all over the world (1). One might say, to paraphrase Churchill, that influenza vaccination is not the best solution to this problem, but it is nonetheless better than all the others. We have no choice but to live with the current situation and to recommend and perform influenza vaccination. For, indeed, the available vaccines do confer a benefit. This is so even if their protective effect, which is indisputably present, is only relative rather than absolute. Moreover, the protective effect varies from year to year, from one age group to another, and from one influenza virus to another among the viruses represented in the vaccines. It bears mention here that a reassessment of the data in an often cited, critical Cochrane Review on the efficacy of influenza vaccination in the elderly revealed a markedly positive protective effect (2, 3).