Variation in Human Papillomavirus Vaccination Effectiveness in the US by Age at Vaccination

This survey study assesses the status and timing of HPV vaccination as self-reported by female participants in the National Health and Nutrition Examination Survey from 2011 to 2018.

given in 3 separate doses over a 6 month period. Have you ever received one or more doses of the HPV vaccine?" and "How old were you when you received your first dose of {Cervarix/Gardasil/Gardasil 9/Gardasil or Gardasil 9/the vaccine}?" The response was coded as an integer age. responded "no" to ever-receiving an HPV vaccine were classified as unvaccinated.
Among individuals who reported "yes" to receiving the HPV vaccination, we classified as vaccinated before sexual debut if they reported no to vaginal sex or if they reported yes to vaginal sex but the age of sexual debut was greater than the age of HPV vaccination.
Individuals who reported yes to HPV vaccination, yes to vaginal sex, and had an age of sexual debut less than or equal to the age of HPV vaccination were classified as These variables are combined into an NHANES self-reported race/ethnicity variable with categories of "Mexican American", "Non-Hispanic Asian", "Non-Hispanic Black", "Non-Hispanic White", "Other Hispanic", "Other Race -Including Multi-Racial". In our analysis, we recoded classifications as "Hispanic" (combining Mexican American and Other Hispanic), "Non-Hispanic Asian", "Non-Hispanic Black", "Non-Hispanic White", "Other Race -Including Multi-Racial".

LITERATURE REVIEW
Various studies and trials have examined the efficacy of the HPV vaccine by age of vaccination. 3-4-5 Using the Costa Rica Vaccine Trial (CVT), Herrero et al. 6 reported no change in vaccine efficacy according to age of vaccination when administered in women who were HPV 16/18-negative at enrollment; however, efficacy decreased as the age of vaccination increased within the full cohort that could include women who were HPV 16/18-positive. Using electronic health records from Kaiser Permanente Northern California, Castle et al. examined the three-year risk of precancer among women aged 21-24 years with low-grade cytology results. 7 He found that women vaccinated before age 18 had lower precancer risk than unvaccinated women and women vaccinated at older ages. Herweijer et al. reported similar findings in Sweden, with women vaccinated before age 17 years having reduced precancer rates compared to unvaccinated women and women vaccinated at older ages. 8 In a microsimulation modeling study, Demarteau et al. estimated the number of preventable cervical cancers through HPV vaccination and showed that as the age of vaccination increases, fewer cervical cancers can be preventable. 9 Falcaro et al. compared to earlier cohorts not eligible for the HPV vaccine. 10 In contrast to prior publications, we examine HPV 16/18 prevalence in individuals who were unvaccinated vs. vaccinated after sexual debut vs. vaccinated before sexual debut. Among individuals eligible for vaccination by age 12 years (ACIP recommends routine HPV vaccination at ages 9 to 12 years. 11 ), we estimated the proportions who were unvaccinated, received vaccination before sexual debut, and received vaccination after sexual debut in the US population.
In our analysis, the maximum time from vaccination until assessment for HPV16/18 is 12 years. Several prior studies have examined the long-term effect of HPV vaccination. Porras et al. 12 found ~95% reduction against HPV16/18 precancers at year 11 in the Costa Rica Vaccine Trial. Lehtinen et al. 13 reported similar long-term efficacy after 10 years in the PATRICIA trial.
Artemchuk et al. 14 reported that anti-HPV 16/18 antibody levels remained stable after 12 years in the Finnish Maternity Cohort.