Methods: We used 2007-2014 NIS-Teen data to examine trends in ≥2 dose varicella vaccination coverage and proportions of adolescents with/without evidence of immunity to varicella. Evidence of immunity included receipt of ≥2 doses of varicella vaccine or varicella disease history. Additionally, using 2014 data, we assessed characteristics of ≥2 dose varicella vaccination coverage: 1) factors associated with ≥2 dose vaccination, 2) timing of receipt of 2nd dose and 3) missed opportunities for 2nd dose vaccination among adolescents who had received 1 prior dose of varicella vaccine.
Results: During 2007-2014, the proportion of adolescents with ≥2 doses of varicella vaccine increased from 8.3% to 66.9% in 13-15 year-olds, and from 3.6% to 56.7% in 16-17 year-olds. The proportion of adolescents with evidence of varicella immunity also increased for both age groups, from 68.0% to 84.1% in 13-15 year-olds and from 78.6% to 83.4% in 16-17 year-olds. Among adolescents who received ≥2doses of varicella vaccine by 2014, a higher proportion of 13-15 year-olds received their 2nd dose at 4-6 years compared to 16-17 year-olds (13.4% versus 3.2%). Factors significantly associated with lower ≥2 dose coverage included non-Hispanic White race/ethnicity; rural residence; living at >133% of the income-to-poverty ratio; no 11-12 year well-child visit; not receiving an adolescent vaccine; and residence in a state with no 2-dose immunization school entry requirement. Among the 2,478 adolescents who received only 1-dose of varicella vaccine, 77.1% (1,922) had at least 1 missed opportunity to receive their 2nd dose; potentially 2-dose coverage could have increased from 79.5% to 94.8%.
Conclusion: The ≥2-dose varicella vaccination coverage and the proportion of adolescents with evidence of immunity to varicella increased during 2007 to 2014, though 16% lacked evidence of immunity in 2014. Though catch-up campaigns have succeeded, decreasing missed vaccination opportunities will help with further improvement.
A. S. Lopez, None
J. Jeyarajah, None
M. Marin, None