HPV Vaccination in a Context of Public Mistrust and Uncertainty: A Systematic Literature Review of Determinants of HPV Vaccine Hesitancy in Europe

"Trust in HPV vaccination is currently being shaken in many European countries, the impact of which is indicated by low and/or decreasing coverage rates."

Human papillomavirus (HPV) vaccination was introduced into national immunisation programmes in all European Union (EU) countries, apart from Poland, between 2006 and 2018. In recent years, HPV vaccination has suffered from growing public distrust and criticism in Europe. The objectives of this systematic literature review were to understand determinants of HPV vaccine hesitancy in the EU, compare determinants of HPV vaccine hesitancy in different European Member States, and examine the importance of safety concerns around HPV vaccination.

A search strategy was developed in November 2016. No restrictions were made on study participants, settings, or publication year. Articles from any EU or European Economic Area (EEA) countries and language were included, although only English language search terms were used. This process led to 103 peer-reviewed and grey literature articles for inclusion in the final analysis. Most studies were conducted with parents (34/103, 10 of which were with mothers only) and healthcare workers, or HCWs (22/103) and reported results from the United Kingdom, or UK (28/103), Italy (12/103), France (10/103), and Sweden (10/103).

Ten thematic categories of determinants of HPV vaccine hesitancy in Europe were identified across the literature: (i) information issues, (ii) concerns about vaccine safety, (iii) issues of trust, (iv) effectiveness of the vaccine, (v) influencers, (vi) issues related to sexual behaviour, (vii) against all or too many vaccines, (viii) access barriers, (ix) perceived need for the vaccine and risk of disease, and (x) fear of injections. These are discussed in detail in article's sub-sections.

The themes most frequently identified in qualitative studies were:

• concerns about potential side effects of HPV vaccination (37 studies with qualitative data),
• beliefs that information about the vaccine is insufficient and inadequate (31), and
• issues related to the sexual health aspects of the vaccine (22).

The categories of concerns raised by the highest average proportions of hesitant participants across all quantitative studies in the review were:

• perceived insufficient and/or inadequate information and knowledge about the vaccine (average of 44.2% of participants across all studies);
• fear of perceived side effects (43.3%);
• mistrust of health authorities, any type of doctor, and new vaccines (39.7%); and
• doubts about the effectiveness of the vaccine (33.7%).

Fear of needles and injections (9.4%) and low perceived need for the vaccine or low risk of HPV/cervical cancer (14.1%) were the categories least often reported by hesitant participants across all studies.

Differences between countries and population groups were identified, although they could be due to differences in study design, variable definitions, and participant selection. That said, perceived insufficient and inadequate information about HPV vaccination was found to be the most important theme in studies with hesitant participants in Romania, Denmark, Italy, Germany, and the UK, whereas fear about potential vaccine side effects predominated the studies in the Netherlands, Greece, Hungary, and France. In Spanish studies, the most commonly reported theme was doubt about the effectiveness of the vaccine.

Concerns about potential side effects of HPV vaccination were commonly reported by hesitant parents and HCWs in studies but came in second for studies with hesitant adolescents. Adolescents included in studies mostly reported dissatisfaction with the quality and quantity of information available about HPV vaccination. This was the second most important issue for hesitant parents included in studies. For studies with hesitant HCWs, the second most commonly reported theme was a low perceived need for the vaccine or a low perceived risk of HPV and/or cervical cancer.

After presenting the findings in detail, the researchers reflect on them, noting that the most frequent concerns reported across studies and among most study participants were a perceived lack of information together with a fear of potential HPV vaccine side effects. This confirms results from previous studies about perceptions of vaccine safety being the most important determinant of vaccine hesitancy for vaccines in general in Europe. While some study participants raised specific concerns about infertility, most reported having general safety fears that they could not explain or specify. This could be a consequence of the vaccine still being perceived as too new and general uncertainty about the vaccine.

Looking more closely into the issue of uncertainty, the researchers note that, although a common approach to uncertainty is to fill information gaps with more facts, mistrust of health authorities and some doctors was commonly reported in this review. This indicates that communication strategies need to go beyond information provision to include efforts to build and maintain public trust.

Specifically, they recommend:

• Communication strategies that engage communities - for instance, by building alliances with civil society or disease associations, organising school information and discussion sessions with parents and peers, and conducting online discussion groups that are overseen and managed by local health professionals.
• Efforts to (i) address HCWs' own hesitancy - for instance, by improving their training on the introduction of new vaccines, and (ii) develop their skills to manage difficult conversations - e.g., through motivational interviewing.
• More research to understand information-seeking behaviours and how individuals appraise and use information about HPV vaccination, as well as to evaluate which communication and engagement strategies are most effective with different population groups (e.g., parents, teenagers, ethnic/religious minorities, or HCWs).
• Evaluations that focus on communication and engagement strategies developed by health authorities, but also on information that the public is exposed to every day, such as television documentaries, online news, or social media.

To elaborate on the latter point, adolescents in some of the studies reported rumours circulating about HPV vaccination. An example is the spread of unverified and subsequently disproved concerns in Denmark through YouTube videos and other social media that HPV vaccine might cause Postural Tachycardia Syndrome (PoTS) and Complex Regional Pain Syndrome (CRPS). To avoid a future confidence crisis, the researchers call for faster research, such as through media monitoring, to identify possible anxiety reactions and to inform time-sensitive strategies - including crisis communication plans - on how to respond to them. Strategies using a combination of social and online media interventions, engagement with mothers and adolescents, and risk communication could be developed and implemented to reinstate public trust in vaccination.