Abstract
BackgroundGardasil®, a quadrivalent vaccine targeting low-risk (6, 11) and high-risk (16, 18) human papillomaviruses (HPV), has been offered to 11–14 year-old schoolgirls in Switzerland since 2008. To evaluate its success and its potential impact on cervical cancer screening, HPV genotypes were examined in 18-year-old girls five years later (sub-study 1) and in outpatients participating to cervical cancer screening before and after vaccine implementation (sub-study 2).MethodsFor sub-study 1, 3726 females aged 18 in 2013 were invited to fill a questionnaire on personal demographics and HPV risk factors and to provide a self-collected cervicovaginal sample for HPV genotyping and Chlamydia trachomatis PCR. Personal data were evaluated by univariable and multivariable statistics. In sub-study 2, the proportion of the vaccine-type HPV among anogenital HPV was examined with archived genotyping data of 8039 outpatients participating to cervical cancer screening from 1999 till 2015. The yearly evolution of this proportion was evaluated by segmented logistic regression.Results690 (18.5%) women participated to sub-study 1 and 327 (8.8%) provided a self-collected sample. Prevalence of Chlamydia trachomatis (4.6%) and demographics confirmed that the subjects were representative of sexually-active Swiss young women. Vaccine (five-year coverage: 77.5%) was preferentially accepted by contraceptive-pill users (P = 0.001) and samples were mainly provided by sexually-active subjects (P < 0.001). The proportion (4%) of the vaccine-type HPV in this population was lower than in sub-study 2 outpatients (n = 849, <26 years old) in the pre-vaccine era (25.7%). The proportion of the high-risk vaccine-type HPV decreased significantly (59%, P = 0.0048) in the outpatients during the post-vaccine era, yet this decrease was restricted to those aged less than 26 years (n = 673, P < 0.0001).ConclusionsThe low proportion of vaccine-type HPV in 18-year-old females and its rapid decrease in young women participating to cervical cancer screening extend the success of HPV vaccination to Switzerland. Our data suggest that cervical cancer screening is now entering a stage of reduced proportion of HPV16 and/or 18 in samples reported positive by cytology. In view of the high likelihood of reduced clinical specificity of cytology, primary screening modalities involving HPV testing and cytology should now be re-evaluated in Switzerland.
Highlights
Gardasil®, a quadrivalent vaccine targeting low-risk (6, 11) and high-risk (16, 18) human papillomaviruses (HPV), has been offered to 11–14 year-old schoolgirls in Switzerland since 2008
The aims of our work were to examine the proportion of vaccine-type HPV among anogenital HPV in sexually-active 18-year-old Swiss females five years after vaccine implementation, and the temporal impact of Gardasil® on this proportion in outpatients participating to CC screening from 1999 to 2015
The low proportion of vaccine-type HPV in 18-year-old females and its rapid decrease in young women participating to cervical cancer screening extend the success of HPV vaccination to Switzerland
Summary
Gardasil®, a quadrivalent vaccine targeting low-risk (6, 11) and high-risk (16, 18) human papillomaviruses (HPV), has been offered to 11–14 year-old schoolgirls in Switzerland since 2008. Infection by high-risk (HR) anogenital human papillomaviruses (HPV) is a necessary cause of cervical cancer (CC) [1]. HPV16 and 18 account for 70% of cases worldwide, while the prototypic low-risk (LR) types, HPV6 and 11, cause the most frequent sexually-transmitted infection (condylomata acuminata). Vaccination against HR HPV targeting girls prior to sexual debut is expected to reduce CC burden, even in those who are not vaccinated thanks to herd immunity [6]. Proving HPV vaccines’ effectiveness against CC is difficult owing to the long delay between initial infection and cancer. A CIN3+ obligatory reporting system is being evaluated for HPV vaccine monitoring in Switzerland [8]
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