Impact of HPV Catch-Up Vaccination on High-Grade Cervical Lesions (CIN2+) Among Women Aged 26-30 in Northern Norway.

BACKGROUND/OBJECTIVES: Human papillomavirus (HPV) is the primary cause of high-grade cervical lesions and cervical cancer worldwide. In Norway, HPV vaccination was introduced in 2009 for seventh-grade girls and extended through a catch-up program from 2016 to 2019 for women born between 1991 and 1996. This study evaluates the impact of the catch-up vaccination program on the incidence of HPV and high-grade cervical lesions in Troms and Finnmark.

METHODS

We analyzed data from 40,617 women aged 26 to 30 who underwent cervical screening between 2009 and 2023 in Troms and Finnmark, including 1850 women with high-grade cervical lesions (CIN2+) on biopsy. Using linear regression, we assessed trends in high-grade lesion incidence per 1000 screened women and the association between vaccination status and HPV-16/18 incidence.

RESULTS

Between 2017 and 2023, the incidence of high-grade cervical lesions significantly decreased: CIN2+ decreased by 33.4%, and CIN3+ decreased by 63.4%. Significant reductions in HPV-16/18-associated high-grade cervical lesions were observed among vaccinated women, with the proportion of CIN2+ cases due to HPV-16 and 18 decreasing from 56.8% in 2017 to 40.7% in 2023, reflecting a 55.8% reduction in the absolute number of cases caused by these high-risk HPV types. Comparing unvaccinated women aged 25-26 in 2016 and vaccinated women in 2023, HPV-16 incidence decreased from 5.1% to 0.1%, and HPV-18 incidence decreased from 3.3% to 0.0%.

CONCLUSIONS

The catch-up vaccination program significantly reduced the incidence of HPV-16/18 and high-grade cervical lesions in Troms and Finnmark, even with the lower vaccination coverage observed in the catch-up program. These findings demonstrate the effectiveness of HPV vaccination programs in reducing HPV infections and associated cervical lesions.