Opportunities and Missed Opportunities for Childhood Influenza Immunization among Insured Children, 2005-2006 Influenza Season

Background:
Influenza immunization rates among children 6-59 months remain low in comparison to other newly introduced childhood vaccines.

Objectives:
Examine visit patterns and missed opportunity rates as potential reasons for low vaccination rates during the 2005-2006 influenza vaccination season.

Methods:
We analyzed Medstat Marketscan claim databases for 316,200 children born in 2001-2004 and continuously enrolled July 2005 – June 2006. For children born in 2004 (age 10-22 months during October-December, 2005) and children born in 2001-2003 (age 22-58 months), we determined percent receiving at least one dose by March 2006 and percent with any visit October-December, 2005). Among unvaccinated children, we calculated the vaccination missed opportunity (MO= any visit other than sick-only where a child was eligible for, but did not receive, an influenza vaccination) rate October-December, 2005.

Results:
At least one dose of influenza vaccine was received by 32,508 (44%) children born in 2004, and 52,539 (22%) of those born in 2001-2003. Among younger children (born in 2004), 84% had any visit October-December 2005 compared with 63% of older children born in 2001-2003; 52% and 16%, respectively, had preventive visits. Among children with visits other than sick-only visits, the MO rate was 22% in the 2004 cohort and 11% in the 2001-03 cohorts. Among children who were vaccinated, the majority of vaccinations occurred during influenza vaccination-only visits (45%) and preventive visits (35%), with 17% given during sick visits. Vaccination and visit rates were highest in the Northeast. MO rates varied little between regions.

Conclusions:
Particularly among the older children in this age group, not having a provider visit during the influenza vaccination season is an important reason for non-vaccination. Along with continued efforts to reduce missed opportunities, strategies effective at bringing parents in for their child's influenza vaccination are needed.