Influenza vaccination options to prevent hospitalization

Vaccination of children against influenza remains a controversial topic despite the substantial morbidity caused by this infection.

To estimate the effect of three different vaccination strategies on preventing hospitalization due to influenza.

A retrospective chart review was conducted of all children admitted to a tertiary health care centre who tested positive for influenza during three consecutive influenza seasons.

The final analysis included 208 cases with an age range of five days to 16.1 years. Seventy-six children were considered 'high-risk' and 132 were considered 'previously healthy'. Length of stay (LOS) ranged from one day to 46 days with a mean of 6.3 days. The mean LOS was 8.6 days for children with risk factors and 4.9 days for those without risk factors. The number of preventable influenza admissions was determined over three years and averaged over one year for the three vaccination strategies. A universal strategy of vaccinating all previously healthy and high-risk children over six months of age would have prevented 118 admissions. Using a selective strategy of vaccinating only children over six months of age with risk factors and a third strategy of vaccinating only two- to six-month-old infants would have prevented 58 and 55 admissions, respectively.

Use of the universal vaccination strategy would have prevented over one-half of the influenza admissions, which was over twice that of targeted vaccination. Until the challenges of implementing universal vaccination are fully understood, targeted vaccination remains an acceptable alternative.