- Tom Jefferson, coordinator (email@example.com)1
- 1 Cochrane Vaccines Field, Anguillara Sabazia, Roma 00061, Italy
- Accepted 21 September 2006
Viral infections of the respiratory tract impose a high burden on society. In the last half of the 20th century, efforts to prevent or minimise their impact centred on the use of influenza vaccines. Each year enormous effort goes into producing that year's vaccine and delivering it to appropriate sections of the population. Here, I will discuss policies on the use of inactivated vaccines for seasonal influenza; the evidence for their efficacy, effectiveness, and safety (“effects”); and possible reasons for the gap between policy and evidence.
Every vaccination campaign has stated aims against which its effects must be measured. The US Advisory Committee on Immunisation Practices produces a regularly updated rationale for vaccination against influenza.1 The current version identifies 11 categories of patients at high risk of complications from influenza (box).
The rationale rests on the heavy burden that influenza imposes on the population and the benefits of vaccination. For example, reductions in cases, admissions to hospital, mortality of elderly people in families with children, contacts with healthcare professionals, antibiotic prescriptions, and absenteeism for children and household contacts are the main arguments for extending vaccination to healthy children aged 6-23 months in the United States.2 Canada introduced a similar policy in 2004.3 Less comprehensive policies recommending vaccination for all people aged 60 or 65 and over are in place in 40 of 51 developed or rapidly developing countries.4 On the basis of single studies, the World Health Organization estimates that “vaccination of the elderly reduces the risk of serious complications or of death by 70-85%.”5 Given the global nature of these recommendations, what type of evidence should we expect …