Influenza vaccination coverage and timeliness among children requiring two doses, 2004-2009.

OBJECTIVE

To assess influenza vaccination coverage and timeliness among children requiring two doses in a season.

METHODS

This study examined seasonal influenza vaccination of 17,800 children from five academically-affiliated clinics in New York City using hospital and city immunization registries. Eligible children were 6 months-8 years and needed two influenza vaccine doses in a given season between 2004-05 and 2009-10. Any (≥ 1 dose) and full (2 doses) vaccination coverage by December 15 and March 31 as well as interval between doses were calculated. Vaccination trends over time, determinants, and missed opportunities were assessed.

RESULTS

Children were primarily Latino and publicly insured. Full coverage by March 31 increased between the 2004-05 and 2009-10 seasons (9% vs. 29%, p<0.001). Few children received both doses by December 15 (2-13%). The interval between doses was almost twice as long as recommended and increased over time (2004-05: 52 days; 2009-10: 64 days; p<0.001). Older age and Latino ethnicity were negative predictors of full vaccination by March 31. Missed opportunities for the second dose were common.

CONCLUSION

Despite improvements, low-income, minority children requiring two influenza vaccine doses remain at risk of incomplete and delayed vaccination. Barriers to and strategies for timely full vaccination should be explored.