Varicella Vaccination Among US Adolescents: Coverage and Missed Opportunities, 2007-2014.

CONTEXT: Since 2007, 2 doses of varicella vaccine have been routinely recommended, with a catch-up second dose recommended for those who received only 1 prior dose.

OBJECTIVE: To examine varicella vaccination coverage with 2 or more doses and the proportions of adolescents with evidence of immunity to varicella (≥2 doses of vaccine or varicella history) during 2007-2014. To assess timing of second-dose receipt, factors associated with 2 or more vaccine doses, and missed second-dose opportunities during 2014.

DESIGN, SETTING, AND PARTICIPANTS: We used data from the 2007-2014 National Immunization Survey-Teen (NIS-Teen), which collects information on adolescents aged 13 to 17 years in the United States.

RESULTS: From 2007 to 2014, varicella vaccination coverage with 2 or more doses increased from 8.3% to 66.9% in 13- to 15-year-olds and from 3.6% to 56.7% in 16- to 17-year-olds. The proportions with evidence of immunity also increased from 68.0% to 84.1% (13- to 15-year-olds) and 78.6% to 83.4% (16- to 17-year-olds). In 2014, 13.4% of 13- to 15-year-olds and 3.2% of 16- to 17-year-olds had received their second dose at 4 to 6 years of age. Factors most significantly associated with lower coverage with 2 or more doses were not having an 11- to 12-year well-child visit, not receiving an adolescent vaccine, and residence in a state with no 2-dose immunization school entry requirement. Seventy-seven percent of 1-dose vaccinated adolescents had 1 or more missed opportunities to receive their second dose; if were they not missed, 2-dose coverage would have increased from 79.5% to 94.8%.

CONCLUSIONS: Levels of varicella vaccination coverage with 2 or more doses and the proportion of adolescents with evidence of immunity increased from 2007 to 2014, though 16% lacked evidence of immunity in 2014. Although catch-up campaigns have succeeded, missed vaccination opportunities persist.