Inactivated influenza virus vaccines in children.

Healthy children aged < or =2 years have hospitalization rates during influenza periods 12 times those of older children and comparable to rates in the elderly population. In 2003, killed influenza vaccines were "recommended" for children with high-risk conditions and were "encouraged" for children aged 6-23 months. Studies involving several thousand children show that split-virus vaccines are safe and immunogenic in healthy children aged > or =6 months and in high-risk children. In children aged < or =9 years, 2 doses of vaccine are required initially to achieve maximum protection. Studies of children aged 6 months to 15 years show vaccine efficacies of 31%-91% against influenza A and 45% against influenza B. Among children attending day care, a reduction in the rate of acute otitis media of 32%-36% was demonstrated. Studies suggest that use of killed vaccines among children is cost-saving. In conclusion, the data show that killed influenza vaccines in children are safe, immunogenic, effective, and potentially cost-saving.