Characteristics of HPV-unvaccinated undergraduate health students in Switzerland, a cross sectional study

Human Papillomavirus (HPV) is responsible for the most prevalent sexually transmitted infection worldwide, which represents a major public health challenge [1]. It is estimated that up to 70% of the sexually active population will be infected with HPV at least once in their life [2]. The highest infection rate is found among 16–25-year-old women. While up to 70% of HPV infections are spontaneously cleared after a few months [3], the persistence of the virus is responsible for the development of cervical cancer, which is associated to HPV in nearly 100% of cases [4]. Cervical cancer is the fifth most common cancer among women aged 20–49 years living in Switzerland [5]. Every year, Switzerland counts as many as 250 cervical cancer and 5′000 cervical precancerous lesion diagnoses [6].

HPV vaccination represents a fundamental primary prevention measure for the development of cervical cancer. The currently available vaccines in Switzerland are Gardasil® and Cervarix®, both of which protect against HPV genotypes 16 and 18, which are responsible for the development of cervical cancer in over 70% of cases [7]. Gardasil®, which has been available on the market since 2007, also covers against genotypes 6 and 11, which are mostly responsible for the development of genital condylomas [8].

The Swiss recommendations for HPV vaccination were first published in 2007, advising the vaccination for all females between the ages of 11 and 14 years while also recommending a catch-up vaccination for women aged 15 to 19 years [9]. The aim of such primary prevention measure is to cover over 80% of the target population. Such recommendations, however, were implemented by each federal canton individually. Such individualized implementation has resulted in disparities in the campaigns and, therefore, in vaccination rates across the country (from 17 to 75% of the targeted population in 2014) [10].

In the Canton of Geneva, the first HPV vaccination campaign tookplace in September 2008. The greatest asset of the campaign in Geneva is the strong involvement of school health services, such as the Service de L’Enfant et de la Jeunesse (SSJ) in public schools, which inform families and offer vaccination to all female school children aged 11–19 years old. According to a study on HPV vaccination carried out 4 years after the first campaign, the majority of 13–14 year-old girls had been vaccinated through the SSJ, thus proving its efficiency [11]. Despite this institutional effort, however, the targeted coverage rate of 80% has yet to be reached. Only a few studies have been carried out with the aim of understanding the reasons for non-vaccination in Switzerland. Moreover, as the campaigns are organised individually by each canton, it is difficult to make generalisations based on the other cantons’ experience and statistics.

The aim of this study was (i) to compare the sociodemographic characteristics of a population of vaccinated and unvaccinated undergraduate female healtcare students in the Geneva canton, (ii) to define the reasons for not having undergone vaccination in the latter group, and (iii) to compare the reasons for non-vaccination to those found in other Swiss cantons.

This is the first study to evaluate the acceptability of the HPV vaccine in Geneva since the introduction of the HPV vaccination in the canton. Our results revealed that 69.4% of our study population was vaccinated against HPV, a rate higher than the rest of Switzerland where, according to the results of a survey conducted in 2016, only 53.6% of women aged 18–24 years were vaccinated [13]. Another study conducted in 2014 found that the French-speaking Swiss regions vaunt a vaccination rate of 68.1%, which is consistent with the rate found in our trial [10]. Moreover, a recent systematic review collecting data from 28 countries pointed out the heterogeneity of vaccination rates worlwide, varing from 2.4 to 94.4% [14].

However, Our results reflect a reality in which, despite the remarkable efforts to reach the optimal vaccination coverage rate, the resistance to the vaccination prevents public health workers from reaching the optimal coverage rate. When looking at reasons for non-vaccination, three of them stood out: fear of side effects (21.6%), parents being against the HPV vaccination (14.4%) and the physician being against the vaccination (8.8%). Similarly, in a study including women aged 18–24 years living in the French-speaking region in Switzerland [10], the main reasons for not having been vaccinated were: thinking it was too late (due to either age, sexual activity, or pathological smear) (52%), fear of side effects (26%), not having received enough information (19%), being against all kinds of vaccination (17%) and having discouraging relatives and friends (15%). Furthermore, a study including 16–20 year-olds living in the Canton of Vaud [9] revealed a lack of information about the HPV infection’s natural history and prevention, as over 70% of the interviewed population felt insufficiently informed about the disease. Moreover, one of the issues highlighted by 29% of the physicians working in private practice in the French-speaking region of Switzerland [8] was the lack of information and support brought by their cantons. A recent study conducted in Switzerland following the first 2 years after the vaccination’s introduction reported that only 117 cases of Gardasil®-associated side effects were found among 420′000 vaccine doses. The same study estimated that 93–98% of CIN2+ lesions caused by 16 and 18 genotypes and 46–70% of the CIN2+ lesions caused by other HPV genotypes could be avoided with vaccination [15]. Such results, which can be used by public health workers to improve the future vaccination campaigns, demonstrate that the lack of information about the HPV infection and its prevention concerns not only the general population, but also health professionals.

Concerning the opinion about the importance of the HPV vaccination, we found that the difference between vaccinated and unvaccinated women was compatible with their immunization status. Over 50.4% of unvaccinated women considered the vaccination as less important than other vaccinations, while 91.9% of vaccinated women considered it as as important as other vaccinations. Another study carried out in Italy obtained similar results among women aged 18–21 years old, thus demonstrating that one of the factors associated with not having been vaccinated was the lower perception of its benefits [16].

A small majority (51.1%) of our population sample had been vaccinated between the ages of 15 and 19 years old, although vaccination for women in this age range was meant to be a catch-up for those who had missed their opportunity to be vaccinated in the first place. Knowing that the moment for the ideal vaccination is before first sexual intercourse, which in our population took place at a median age of 17.2 years old, baseline vaccination for all 15–19 years-olds seems to be a reasonable target to improve prevention. Nevertheless, the median age when receiving the first vaccine dose in our study population was 14.8 years old. The small percentage of vaccinated women after the age of 20 years old (4.2%) is not surprising considering that the campaign mainly targets the younger part of the population. Such results are in line with those of a study [6] evaluating the age at the first dose of HPV vaccine in a population of Swiss women, which found that the vaccination rates were 54.4% for women between aged 15–19 years old, 39.8% for women aged 11–14 years old, and 5.8% for women older than 20.

When studying the sociodemographic characteristics of our population, only nationality was found to be significantly associed to vaccination status, as a greater proportion of women coming from Geneva and its surroundings were vaccinated when compared to women coming from other cantons and countries. Given the difference of the vaccination campaigns and policies in other cantons and countries, such finding highlights the efficacy of the vaccination campaign in the canton of Geneva, where a particularly active role was played by the SSJ in public and private schools. Other studies have confirmed that, when the SSJ was involved in vaccination campaigns, as is the case in other French-speaking cantons in Switzerland, such finding resulted in better vaccination rates than those in the German-speaking part of Switzerland [9].

One strength of our study was given by the fact that we chose a population of young, future healthcare providers, whose opinion is fundamental in the view of spreading the vaccination uptakein the near future. In addition, this population sample of young adults has never been studied in such geographical area.

One limitation of our study was the sample’s relatively small size, which limited the power of some of our observations. A selection bias also may have occurred, as all the participants not only had a high educational degree but also studied medical and health sciences, which does not reflect the heterogeneity of the general population. Additionally, the HPV kits were offered to the students who proactively expressed an interest to participate in the study, excluding the girls possibly having another opinion about the HPV vaccination. Finally, 46.3% of our participants had not checked their vaccination record to answer the questionnaire, an aspect which may have altered some of the study results.

The suboptimal HPV vaccination rate among our study population of undergraduate women shows that, despite the vaccine’s proven efficacy, the coverage rate is still far from reaching 80%. The majority of vaccinated women in our study population came from the Geneva Canton, a finding which further highlights the discrepancies in vaccination campaigns in the country. Proactive education about the HPV infection’s natural history and the vaccination’s role, to be delievered by the women’s personal healthcare providers, represents a fundamental step in increasing the vaccination coverage rate across the country.