HPV vaccine impact: genotype-specific changes in cervical pre-cancer share similarities with changes in cervical screening cytology.

BACKGROUND

After human papillomavirus (HPV) vaccine introduction, declines in the prevalence of HPV vaccine types have been observed in screening cytology, but data from the United States describing HPV type-specific changes in cervical intraepithelial neoplasia (CIN) grades 2-3 and adenocarcinoma in situ (CIN2/CIN3/AIS) are limited.

METHODS

A statewide sample of individuals with cervical biopsies was selected for broad-spectrum HPV genotyping. CIN2/CIN3/AIS incidence and prevalence were calculated for type-specific high-risk HPV (hrHPV) among individuals aged 15-29 years. Weighted incidence rate ratios (IRR) and relative differences in prevalence (RDP) were computed to compare 3 time periods: 2006-2009 (Cohort 1 [C1], n = 4121), 2012-2015 (C2, n = 2194), and 2015-2018 (C3, n = 1481).

RESULTS

When comparing C1 vs C3 among those aged 21-25 years, statistically significant reductions in hrHPV type-specific CIN2/CIN3/AIS incidence were observed for HPV16, HPV18, HPV31, and HPV33, with corresponding IRRs of 0.4 (95% confidence interval [95% CI] = 0.3 to 0.4), 0.3 (95% CI = 0.1 to 0.7), 0.6 (95% CI = 0.5 to 0.9), and 0.4 (95% CI = 0.1 to 0.8), respectively. The RDP comparing C1 vs C3 for HPV16/18-positive CIN2/CIN3/AIS was -43.8% (P < .001). When excluding HPV16/18 or HPV16/18/31/33 from all hrHPV types, the RDP was +56.6% and +92.5% (P < .001), respectively.

CONCLUSIONS

hrHPV type-specific CIN2/CIN3/AIS incidence decreased with statistical significance for vaccine types HPV16/18 and for HPV31 and HPV33. Although the HPV vaccine is highly beneficial and a top priority for preventing HPV-related cancer, the long-term vaccine impact in cohorts receiving the 4-valent HPV vaccine requires continued follow-up to assess genotype-specific distributions in the remaining CIN2+ lesions and cancers.