Is vaccine type seropositivity a marker for human papillomavirus vaccination? National Health and Nutrition Examination Survey, 2003–2010✩

OBJECTIVE Since 2006, human papillomavirus (HPV) vaccination has been routinely recommended for adolescent females in the USA. The quadrivalent vaccine induces long-term seropositivity to HPV 6/11/16, which may be useful as a marker for HPV vaccine coverage. METHODS We evaluated vaccine type seropositivity (i.e., seropositivity to HPV 6/11/16 with or without HPV18) among females aged 14-59 years participating in the 2003-2010 National Health and Nutrition Examination Survey (cross-sectional, nationally representative surveys). We compared pre-vaccine era (2003-2006) to vaccine era (2007-2010) seropositivity and assessed agreement between vaccine era seropositivity and reported vaccination by kappa statistic. RESULTS Seropositivity was 1.0% among 2151 females in the pre-vaccine era and 22.1% among 1420 females in the vaccine era (p < 0.001); 23.1% of vaccine era females reported receipt of one or more HPV vaccine dose. Seropositivity and reported vaccination had high agreement (kappa = 0.79; 95% confidence interval 0.74-0.84). Among seropositive females, 14.5% reported no vaccination. CONCLUSION The increase in vaccine era seropositivity likely reflects vaccination uptake. Our study suggests seropositivity to HPV 6/11/16 may be a useful marker for vaccination coverage in adolescent and young adult females. Discordance between seropositivity and reported vaccination may be explained by inaccurate reporting and/or natural exposure to HPV.