Oral and genital human papillomavirus (HPV) prevalence in young women and men attending a youth clinic in Stockholm, Sweden : A follow up study after the introduction of HPV vaccination

Sammanfattning: Background and Aim: In 2010 HPV vaccination was subsidized in Sweden and in 2012 a national vaccination program against HPV16, 18, 6 and 11 was launched for girls ages 10-12 years. In parallel was a catch-up vaccination program for young women. To investigate base line HPV cervical and oral prevalence in non-vaccinated youth two studies were performed at a youth clinic in Stockholm 2008-2011. This project initiated 2013 aimed to follow HPV prevalence in youth since the previous studies, in the same population.   Materials and Methods: 117 women, of which 73% were HPV catch-up vaccinated donated 93 cervical samples and 117 oral samples, and 54 unvaccinated men donated 54 oral samples and 47 urinary samples. All samples were tested for 27 HPV types with a PCR based system and the data was compared to that obtained in 2008-2011. The categorical Fishers exact test was used for statistical analysis due to HPV-positive samples being n< 5 for certain types.  Results and Conclusion: HPV16 cervical prevalence was significantly lower in the HPV vaccinated women compared to unvaccinated women (7% and 27% respectively, p=0.033) in the 2013 group. For HPV18 and HPV6 there was a significantly lower prevalence in the 2013 vaccinated group compared to the 2008-2010 unvaccinated group (1.5% vs. 10% respectively, p=0.021 and 1.5% vs. 8% respectively, p=0.048). Overall oral HPV prevalence for both genders, was lower in the 2013 group compared to that of 2009-2011, (2.3% and 9.1% respectively, p=0.005). Male urinary prevalence was low (6%) and not efficient to follow changes in specific HPV types. The data indicate that HPV catch-up vaccination was gradually exhibiting an effect, with significant decrease of cervical HPV16 prevalence.