Commentary

Influenza vaccine is clearly cost effective in elderly people and those with chronic cardiac or respiratory disease. It reduces hospital admissions, respiratory mortality, and all cause mortality.¹ Important potential benefits also exist in vaccinating healthy adults between 18 and 64 years of age against influenza, including reductions in influenza-like illness (ILI), avoidance of disruption in daily living, decreases in work absenteeism, and reduction in physician visits for ILI.² From a societal perspective, the average costs range from a net saving of US$46.85 per vaccinated person to a net cost of $11.17 per person. The difference depends in part on the factors inserted in the sensitivity analyses and the range of the variable assumptions for vaccine efficacy, infectivity, and cost at different vaccination sites (ie, private office v work site).^2,3 When little or no match exists between the vaccine and epidemic strain, the benefit is small to nil.

Demicheli et al show that an influenza vaccine is effective in reducing serologically confirmed cases of influenza A but is less effective in reducing cases of clinical influenza. However, because clinical influenza is a syndrome caused by several viruses, including respiratory syncytial, parainfluenza, and other viruses, efficacy using the outcome of clinical influenza will typically be underestimated; serological confirmation is a more reliable outcome.

This review confirms that the inactivated influenza vaccine is an effective method for preventing influenza in healthy adults. When the influenza vaccine supply permits, healthy young adults would benefit by receiving the inactivated influenza vaccine.