Patterns of Vaccination among Adolescents: Single and Concomitant Administration of Recently Licensed Vaccines in the Vaccine Safety Datalink (VSD) Population

Background:
Since 2005, three new vaccines – tetravalent meningococcal conjugate (MCV4); tetanus, diphtheria and acellular pertussis (Tdap); and quadrivalent human papillomavirus (qHPV) – have been licensed and recommended for adolescents. Few studies have evaluated the administration of these vaccines, including provider compliance with ACIP recommendations.

Objectives:
To describe single and concomitant (defined as two or more vaccines administered at the same visit) vaccination of three recently licensed vaccines among adolescents.

Methods:
Vaccination history was collected for persons aged 7 to 26 years who received at least one vaccination at a participating VSD site between June 2006 and July 2008. The population was divided into the following age groups: 7-10 years, 11-12 years, 11-18 years, and 19-26 years. For each vaccine, the number of vaccine visits and the proportions of single and concomitant administration were determined; the most common vaccine combinations were also quantified. Analyses were conducted to determine the presence of significant differences in administration by provider type.

Results:
Among 11-18 year olds, there were 576,410 visits where any adolescent vaccine (MCV4, Tdap or qHPV) was administered. At 45% of those visits only a single vaccine was given, despite recommendations for concomitant administration of multiple vaccines. Tdap and MCV4 were administered alone in 10% and 8% of all visits, respectively. At 30% of visits where the first dose of qHPV was administered, it was given alone. The most common concomitant vaccine combination was MCV4+Tdap, which accounted for 7% of all visits. Family physicians were significantly less likely to administer two or more vaccines at one visit compared with pediatricians.

Conclusions:
The large proportion of adolescent visits where only one vaccine is given suggests that there may be missed opportunities for vaccination, particularly at adolescent visits to family physicians. Findings could direct educational efforts targeted to providers, parents, and/or adolescents.