Two-Dose Varicella Vaccine Coverage In Public Schools: New York City, 2009-2010

Background: In 2006, the Advisory Committee on Immunization Practices (ACIP) adopted a two-dose varicella vaccine recommendation for children aged <13 years. NY State law mandates 1-dose of varicella vaccine for school entry. Since 2006, varicella cases reported to the NY City (NYC) Department of Health and Mental Hygiene school-based surveillance system declined 72%.

Objectives: To determine varicella vaccination coverage in a sample of NYC public school children.

Methods: All students (N=92,800) in 121 NYC public schools participating in active varicella surveillance were included. Vaccination records in the Department of Education and NYC Citywide Immunization Registry databases were merged. Varicella doses administered ≥361 days from date of birth, and/or given ≥28 days after another varicella dose were considered valid.  Valid doses were used to calculate varicella coverage. Two-dose varicella vaccine coverage for children aged <10 and 10-17 years was compared; age <10 years was chosen because this group was eligible to receive a 2^nd dose at the recommended age after the 2006 ACIP recommendation.

Results: Overall, ≥1dose coverage was 93% and ≥2 dose coverage was 56%; 2% of students had documented immunity to varicella and no vaccinations. Sixty-five percent of children aged <10 years had ≥2 doses of varicella versus 51% of children aged 10-17 years (p<0.001). Race/ethnicity data was available for >98% of students. Two or more-dose coverage was significantly higher in each of Asian/Pacific Islanders (60%), non-Hispanic Blacks (57%), and Hispanics (60%) compared to non-Hispanic Whites (43%), (p<0.001).

Conclusions: Higher ≥2 dose coverage among children aged <10 years may represent failure of older students to receive catch-up varicella doses since 2006, or better reporting among younger children. Additional analyses will better characterize differences in coverage by race/ethnicity and other factors. A 2-dose varicella vaccine requirement at school entry would likely improve coverage.