Joske Hoes (Netherlands)
RIVM CibPresenter of 3 Presentations
HIGH VACCINE EFFECTIVENESS AGAINST PERSISTENT INFECTIONS UP TO EIGHT YEARS POST THREE DOSES OF BIVALENT HPV VACCINATION IN THE NETHERLANDS (ID 715)
Webcast
TRENDS IN HPV INFECTION PREVALENCE UP TO 8 YEARS AFTER GIRLS-ONLY HPV16/18 VACCINATION IMPLEMENTATION IN THE NETHERLANDS: A REPEATED CROSS-SECTIONAL STUDY IN STI-CLINIC VISITORS (ID 735)
Abstract
Introduction
The population effects of HPV vaccination extend beyond direct protection among vaccinated individuals; evidence for herd effects unfolds as follow-up time after vaccination increases and infection dynamics change. Here, we provide an overview of observed trends for 25 HPV types up to eight years post vaccination implementation in the Netherlands, where the bivalent HPV16/18 vaccine has been offered to (pre)adolescent girls since 2009 with moderate vaccination coverage (between 49-61%).
Methods
In this updated analysis, we used data from the PASSYON study, conducted in STI clinics throughout the country. The study was initiated in 2009 (pre-vaccination) and repeated in 2011, 2013, 2015, and 2017 among clinic visitors aged 16-24 years. We studied genital HPV prevalence over time among heterosexual men, all women, and unvaccinated women using Poisson GEE models, adjusted for known confounders. Type-specific trends were studied for all high and low-risk genotypes detected by the SPF10-LiPA25 platform.
Results
In this analysis, we included 2,414 heterosexual men and 6,354 women (of whom 64.7% reported to be unvaccinated). Significant declines in HPV16 and 18 were observed for all women as well as heterosexual men and unvaccinated women (crude prevalences in Figure 1). Declines in cross-protective HPV types were observed among women (for HPV31 and 45) and heterosexual men (for HPV31). Focusing on the high-risk HPV types, we observed significant increases in HPV56 among all women and in HPV52 among unvaccinated women (Table 1). 
Conclusions
Our results provide compelling evidence for herd effects against vaccine and cross-protective HPV types among men (first-order effect) as well as herd effects against vaccine types among unvaccinated women (second-order effect). These results are promising regarding the eventual impact of girls-only HPV vaccination as they demonstrate that herd effects become noticeable throughout the population even with moderate vaccination coverage. Increases in other high-risk HPV types require continued monitoring of infection dynamics.
GENITAL HPV PREVALENCE AMONG TWO-DOSE BIVALENT HPV VACCINE ELIGIBLE GIRLS IN THE NETHERLANDS AFTER THREE YEARS OF FOLLOW-UP: THE HAVANA2 COHORT (ID 723)
Abstract
Introduction
The Netherlands introduced the bivalent HPV vaccine into the National Immunization Program as a girls only vaccine in a three-dose schedule in 2009. Following the EMA advice in 2014, the Netherlands was one of the first countries that switched towards a two-dose schedule. Alongside this implementation, a population-based longitudinal cohort was established: HAVANA2. Here, we describe participant characteristics and compare HPV prevalence among vaccinated and unvaccinated girls over three years of follow-up (3y-FU).
Methods
In 2016, we invited 39261 girls who were eligible for the two-dose schedule in 2014 (birth cohort 2001) for participation in HAVANA2. Of these, 2571 girls provided informed consent. Yearly, participants provided a vaginal self-swab and a questionnaire on demographics and sexual behavior. Using the HPV-DEIA-LiPA25 platform, genital swabs were genotyped to study prevalence of high-risk (including HPV16/18) and low-risk HPV types.
Results
In total, 2121 girls provided a vaginal self-sample and a questionnaire at least once in the first three years of study (52.9% vaccinated). 1378 participants provided materials for all 3y-FU. The majority of the study population was Dutch (88.9%) and 84.3% reported to be sexually naive at study entry. Preliminary results show that the high-risk HPV type with the highest prevalence was HPV51 both for vaccinated (1.7%) and unvaccinated participants (2.6%) at 3y-FU. The cumulative prevalence over three years of HPV16/18 infections was low: 0.2% among vaccinated and 1.5% among unvaccinated, respectively.
Conclusions
After 3y-FU, the total number of infections was low. Nevertheless, the decreased high-risk and vaccine type HPV prevalence among vaccinated compared to unvaccinated girls indicate the first effect of the two-dose schedule providing protection in a population setting. Follow-up of this cohort is planned for at least two more years aiming to estimate vaccine effectiveness estimates against (persistent) high-risk HPV infections for a two-dose schedule.