BACKGROUND AND PURPOSE:

• While clinical trials showed the HPV vaccine is highly effective, its real-world impact especially among high-risk adolescents and young women is less well understood
• DeSieghardt et al. (JAMA Pediatrics, 2025) examined effectiveness and herd protection in this high-risk population over the first 17 years following HPV vaccine introduction

METHODS:

• Cross-sectional study
  • Data from 6 surveillance studies from 2006 to 2023
• Population
  • A consecutive sample of sexually experienced adolescent girls and young women aged 13 to 26 years
• Exposure
  • HPV vaccination status
    • Defined as receipt of ≥1 vaccine dose
  • HPV vaccine type
    • 2-valent vaccine (2vHPV) | 4-valent vaccine (4vHPV) | 9-valent vaccine (9vHPV)
• Study design
  • The prevalence of vaccine-type HPV was compared in vaccinated participants from studies 2 through 6, vs unvaccinated participants in study 1
  • Inverse probability of treatment weighting with propensity score was used to balance comparison groups
• Primary outcomes
  • Vaccine effectiveness
  • Herd protection

RESULTS:

• 2335 participants
  • Mean age: 18.9 (SD, 2.7) years
  • African American: 65.4% | Asian: 0.6% | Native American: 0.3% | White: 24.9% | Multiracial: 6.5% | Hispanic: 7.4%
  • Reported a STI history: 51.2% | Reported ≥2 male sex partners: 78.9%
• Vaccination rates increased from 2006 to 2023
  • 2006: 0% | 2023: 82.1%
• Among vaccinated participants, positivity for HPV types decreased between 2006 and 2023
  • 2vHPV studies
    • 2006: 27.7% | 2023: 0.4%
    • Relative difference 98.4%
  • 4vHPV studies
    • 2006: 35.4% | 2023: 2.1%
    • Relative difference 94.2%
  • 9vHPV studies
    • 2006: 48.6% | 2023: 11.8%
    • Relative difference: 75.7%
• Positivity for different HPV types also decreased among unvaccinated participants, though gains were smaller than vaccinated participants
  • 2vHPV studies
    • 2006: 25.8% | 2023: 7.3%
    • Relative difference: 71.6%
  • 4vHPV studies
    • 2006: 25.3% | 2023: 6.1%
    • Relative difference: 75.8%
  • 9vHPV studies
    • 2006: 42.7% | 2023: 31.3%
    • Relative difference: 27.2%
• There were significant reductions in the odds of at least 1 HPV type for 2vHPV, 4vHPV and 9vHPV studies
  • 2vHPV studies
    • All participants: Adjusted odds ratio (aOR) 0.03 (95% CI, 0.01 to 0.07)
    • Vaccinated participants: aOR 0.01 (95% CI, <0.01 to 0.05)
    • Unvaccinated participants: aOR 0.23 (95% CI, 0.08 to 0.63)
  • 4vHPV studies
    • All participants: aOR 0.06 (95% CI, 0.03 to 0.10)
    • Vaccinated participants: aOR 0.04 (95% CI, 0.02 to 0.08)
    • Unvaccinated participants: aOR 0.19 (95% CI, 0.07 to 0.52)
  • 9vHPV studies
    • All participants: aOR 0.22 (95% CI, 0.16 to 0.31)
    • Vaccinated participants: aOR 0.14 (95% CI, 0.09 to 0.21)

CONCLUSION:

• 17 years after the introduction of HPV vaccination, population-level vaccine effectiveness and herd immunity remain high
• The authors state

Our findings provide new evidence of robust effectiveness and herd protection in sexually experienced adolescent girls and young women at relatively high risk of HPV and associated cancers, even if they did not receive the recommended 2- or 3-dose vaccine series

Learn More – Primary Sources:

Population-Level Effectiveness and Herd Protection 17 Years After HPV Vaccine Introduction