Population-based prevalence, type- and age-specific distribution of HPV in women before introduction of an HPV-vaccination program in Denmark.

Knowledge about the prevalence of human papillomavirus (HPV) on a population level is important. We conducted a large population-based study in Denmark to determine the overall and age-specific HPV prevalence, and HPV type distribution in women. Liquid-based cytology samples (SurePath) were collected consecutively. HPV testing was performed with Hybrid Capture 2 (HC2; Digene) (high-risk and low-risk probes), and LiPA (Innogenetics) was used for genotyping. We analyzed samples from 11,617 women; 94.0% had normal cytology, 4.3% atypical squamous cells of undetermined significance or low-grade squamous intraepithelial lesion and 1.6% had high-grade squamous intraepithelial lesion (HSIL). The HPV prevalence was 26.4% with a peak in women 20-24 years (50.2%) and then decreased without a second peak in older women. Among the youngest women (15-19 years), 14% had HPV 16/18 and 16% had HPV 6/11. Prevalence of high-risk HPV types increased from 19.2% in women with normal cytology to 100% in women with cervical intraepithelial neoplasia grade 3 (CIN3)/cervical cancer. HPV 16 was the most prevalent type (6.0% of all women), and was also the most prevalent in women with HSIL (35.1%) and CIN3 (53.2%). Other common HPV types in women with CIN3 included HPV 52, 51, 31, 33 and 18. HPV 16/18 alone was present in 23% of CIN3 lesions and 67% of cervical cancers, and HPV 16/18 together with other high-risk HPV types was present in 41% of CIN3 lesions. This suggests that an efficacious HPV 16/18 vaccine will have a substantial preventive potential in the general female population.