The Centers for Disease Control and Prevention has reported that data from a nationwide telephone survey indicate that only 18% of children aged 6 months to 2 years were fully vaccinated for influenza in the 2004–2005 influenza season.
To be considered “fully vaccinated,” a child must have received two injections in the September-December 2004 period if he or she had never been vaccinated, or only one injection in that period if the child had any history of influenza vaccination.
The portion of children nationwide who had received at least one dose of flu vaccine in the period was 33% (MMWR 2006;55:1081–5).
The state with the largest portion of fully vaccinated children in this age group was Nebraska, with 33%. The state with the least was Idaho, with 6%. Children in large cites were even less likely to be fully vaccinated, however; only 3% of children under age 2 years in Detroit were fully vaccinated, compared with 15% of those in Michigan as a whole.
Notably, the September-December period of 2004 coincided with a national shortage of vaccine, which the CDC recently reported should not occur this season, because there will be two additional manufacturers supplying vaccine, bringing the total to four, whereas as there where only two manufacturers in the 2004–2005 season. However, the CDC's Advisory Committee on Immunization Practices that year deemed children aged 6–23 months as a priority population for vaccination, and thus the lack of supply in theory should not have affected this group as much as others.
The period in question was the first for which routine annual influenza vaccination was recommended (rather than merely encouraged) for children in this age group. Since then, the recommendation has been expanded to include children up to age 59 months.