[Target groups for influenza vaccination]

To assess target groups for influenza vaccination.

The target groups for influenza vaccination specified in the recommendations of the US Advisory Committee on Immunization Practices (ACIP) were summarized and compared between 1997 and 2006.

Principal changes after the 1997's recommendation are as follows: 1) all children aged 6-59 months became included into the high risk group for active vaccination; 2) recommendation for vaccination timing of pregnant women was extended from those at the second trimester or after to all women who are pregnant during the influenza season; 3) persons with neuro- or muscular-disorders and therefore prone to development of respiratory systems or aspiration pneumonia became included into the high risk group; 4) a category with increased risk to visit a clinic, hospital or emergency department due to influenza-related symptoms was newly established, covering children aged 24-59 months and persons aged 50-64 years; 5) healthy household contacts and caregivers of children aged 0-59 months were included into the group who can transmit influenza to persons in the high risk group; 6) people likely to transmit influenza to persons in the high risk group were classified into 3 categories (health-care providers, household contacts and caregivers, and those in close contact with children aged 0-59 months).

The ACIP has gradually expanded the target populations for routine influenza vaccination. The most notable change during past 10 years seems to be the recommendation for inclusion of all children aged 6-59 months and people in close contact with babies for active vaccination.