Background: The Spring 2009 H1N1 influenza epidemic disproportionately affected younger populations with 5-19 year olds accounting for over half of confirmed cases in Philadelphia. In fall 2009, the Philadelphia Department of Public Health (PDPH) launched a comprehensive program to vaccinate children and other priority groups. Vaccine was offered in 389 schools (public, private, charter, and catholic) and through pediatric health care provider offices (HCPs).
Objectives: To assess overall H1N1 vaccine coverage of children in Philadelphia and to consider differences in the populations of children vaccinated by the school located vaccine (SLV) program and HCP offices.
Methods: All analyses utilized US Census Bureau statistics along with data on H1N1 vaccine administrations that were recorded in the KIDS Immunization Registry.
Results: Of the approximately 289,660 5-18 year olds in Philadelphia, 79,722 (28%) received H1N1 vaccine. Of the vaccinated children, 35,169 (44%) and 44,553 (56%) were vaccinated by the SLV program or in the HCP offices, respectively. Stratification by age revealed that 47% of 5-9 year olds, 49% of 10-14 year olds, and 29% of 15-18 year olds received H1N1 dose 1 from the SLV program. Stratification by gender showed that 45% and 43% of females and males, respectively, received their 1st H1N1 dose from the SLV program. Of the 5-9 year old school aged children eligible for H1N1 dose 2, 15,770 (42%) received their 2nd dose. Seventy-five percent of dose 2 recipients were vaccinated through the SLV program.
Conclusions: The Philadelphia SLV program accounted for almost half of the 1st H1N1 doses administered to 5-14 year olds and three quarters of the 2nd H1N1 doses administered to 5-9 year olds. Thus, SLV is a viable, large-scale vaccination method that should be considered in the event of future epidemics. However, the low proportion of 15-18 year old adolescents vaccinated by SLV does suggest that additional strategies should be developed to reach this population.