Under-vaccinated groups in Europe and their beliefs, attitudes and reasons for non-vaccination; two systematic reviews

Vaccination programmes have been shown to reduce health inequality worldwide [1]. However, despite national immunisation programmes in Europe, some groups remain incompletely or un-vaccinated (“under-vaccinated”), with underserved minorities and certain religious/ideological groups repeatedly being involved in outbreaks of vaccine preventable diseases (VPD) [2].

As an example, in 2004, a rubella outbreak occurred within an under-vaccinated religious community in the Netherlands [3], which spread to Canada [4, 5] and led to cases of congenital rubella syndrome [4, 6]. These outbreaks in under-vaccinated groups sometimes cause “spill over” disease in the general population as occurred during two measles outbreaks. One occurred in Germany in 2008, from the anthroposophic community to the general population who had vaccination coverage below the World Health Organisation (WHO) recommended level [7]. The second one, in the Netherlands in 1999–2000, started among unvaccinated members of Orthodox Protestant Reformed churches and spread to children of vaccinating parents, but whose children were susceptible as they were still too young to be vaccinated [8, 9]. Between May 2013 and February 2014, another measles outbreak was ongoing in the Netherlands among the same religious community with 2700 reported cases [10].

The World Health Organization Regional Office for Europe (WHO/EURO) has set several goals for elimination of endemic measles and rubella in Europe [11]. However, achieving this goal and improving VPD vaccination coverage in general remains difficult as long as clusters of large under-vaccinated groups (UVG) still exist in various countries. In addition, in case of a major vaccine preventable outbreak, like the 2009 influenza A(H1N1) pandemic, these groups are likely to refuse any new vaccination which may be advised by the government/public health authorities. Therefore, they can form a susceptible pool of individuals at increased risk to acquire the VPD, and can act as a focus for and multiplier of the infectious agent, with subsequent spread to the general population.

For communicable disease control it is especially the social clustering of non-vaccinated individuals that increases outbreak risk. Clustering of non-vaccinated individuals is found in various groups in Europe. Most of these UVGs are labelled as ‘hard-to-reach’. However, not all groups are hard-to-reach and each group has its specific reasons and even individuals with in a group may differ for which specific approaches are needed and not general ones. Knowledge on the specific reasons for low vaccination uptake among the various UVGs, might facilitate communication based on their (information) needs. The Strategic Advisory Group of Experts (SAGE) on immunization has defined determinants of vaccine hesitancy (i.e. this term refers to delay in acceptance or refusal of vaccines despite availability of vaccination services) worldwide, both for general populations and/or groups. They divided the determinants into three categories: 1. Contextual influences (e.g. religion/culture/gender/socio-economic, communication and media environment), 2. Individual and group influences (e.g. personal experience with vaccination, health system and providers trust), and 3. Vaccine/vaccination specific issues (e.g. risk/benefit (epidemiologic and scientific evidence), costs) [12]. In this study we focus on the specific determinants of vaccination uptake in under-vaccinated groups, which can also include determinants of poor availability. While the only intervention to increase vaccination uptake addressed in this study is on communication, we do recognize that communication might not be the only intervention needed, and that other interventions such as changes in the delivery strategy of vaccines might have high impact. But nevertheless, in all cases communication is essential.

This study is part of one of the Work Packages (WP) of the EU-funded project “Effective Communication in Outbreak Management: development of an evidence-based tool for Europe”, which started in 2011. The aim of our contribution to the project is to identify vantage points for communication strategies and present suggestions for communication with UVGs that can be used effectively by health professionals and agencies throughout Europe, in case of an epidemic or pandemic of a VPD. To that purpose the focus in this paper is on how to identify the UVGs in Europe and the description of factors (beliefs, attitudes and reasons) for poor uptake of vaccination in order to know with whom and how to communicate.

We performed two systematic reviews as to our knowledge this has not been done before. The objective of the first review was how to identify UVGs in Europe and to describe the UVGs, and of the second to describe beliefs, attitudes and reasons of non-vaccination of these UVGs identified by the first review and a comparison of the factors among the UVGs (both qualitative and quantitative studies were included).

Public Health authorities in the European region face challenges with outbreaks among UVGs, and equally in efforts to meet the requirements set by the WHO for eliminating measles and rubella in the near future. Elimination can only be obtained through high vaccination coverage in the respective countries. As long as pockets of low vaccination coverage remain in many European countries, outbreaks of VPDs will continue to occur, and elimination will be infeasible as long as there are UVGs. These pockets of low vaccination coverage may occur through clustering once exemption begins to take hold in a particular community [58]. Besides outbreaks will occur within these groups, they can also act as a source for further transmission to the general population. Increasing vaccination uptake in these groups starts with talking with the groups and develop together with them appropriate communication. We found several common beliefs related to non-vaccination in these groups that could help to find policy vantage points for communication with these groups.

Looking at outbreaks and low vaccination coverage studies among groups and communities, we identified five UVGs throughout Europe that represent a significant number of people: Orthodox Protestants in the Netherlands [13, 14] (around 250,000 persons), Anthroposophists mostly in Austria, Germany and bordering countries (numbers not available), Roma mainly in Central and South-eastern Europe [2, 25] (6–8 million), Irish Travellers in the United Kingdom and Republic of Ireland [2] (120,000–340,000) and Jewish Orthodox in the United Kingdom and Belgium [47, 48] (around 30,000). All five UVGs experienced measles outbreaks. Measles is highly contagious and requires at least 95% vaccination coverage to maintain herd immunity [59], which could explain the higher number of measles outbreaks (35) that were described compared to rubella (3) and mumps (2) outbreaks. In the context of low vaccination coverage, large VPD outbreaks will continue to occur in these groups, with the risk of spreading disease to vulnerable individuals in the general population (vaccinated or not), as has been seen in several previous measles outbreaks [8].

From the factors-oriented literature search, we conclude that there is as yet little published English-language literature specifically addressing beliefs, attitudes and reasons regarding non-vaccination among these groups, as we only found five articles. These five articles were based on empirical research, using both qualitative and quantitative study designs: one among Orthodox Protestant parents, two among Anthroposophists and two among Orthodox Jewish parents. We have not identified research published in the English international literature aiming to study mainly beliefs, attitudes and reasons regarding non-vaccination among the Roma and the Irish Travellers communities. However, some reasons for non-vaccination were described in the eight additional articles selected from the first literature search. A variety of beliefs and objections to vaccination were reported among each group. Not all members have the same beliefs, also called within-group heterogeneity. On the other hand, some similar beliefs were shared between different groups, also called between-group homogeneity. The most frequently mentioned shared reasons for not vaccinating their children are: the perceived non-severity of the disease, the perceived un-safety of the vaccine (e.g. the fear of side effects and misconceptions), and the need for more information or the lack of information about for example risks of vaccination. Apart from these common factors for non-vaccination, each UVG has its own specific factors. Low vaccination coverage for certain diseases among the Anthroposophists could be explained by their specific philosophy of a healthy lifestyle. For Orthodox Protestant, firm trust in Divine Providence seems to be the most important reason for not being vaccinated. This religious factor is incidentally also found among the Orthodox Jewish communities, although Jewish scholars have rejected arguments that medical interventions interfere with divine providence [60]. Whereas low vaccination coverage among Anthroposophist, Orthodox Protestants and Orthodox Jewish communities may be explained by their beliefs, our findings from the literature suggest that low vaccination coverage among Roma and the Irish Travellers communities is predominantly explained by poor access to health care services due to mobility.

As the objective of our contribution to the EU project mentioned in the introduction was to find vantage points for communication tactics with UVGs in case of an epidemic, we searched for factors (beliefs and attitudes) regarding non-vaccination of these groups with regard to epidemics. No literature has been found on UVGs in the framework of pandemics, also not with regard to the influenza A(H1N1) pandemic in 2009. We did find literature on factors for non-vaccination against pandemic influenza A among the general population as the general vaccination uptake during the 2009 pandemic was low in various countries [61]. Strikingly, most of the factors for non-acceptance among UVGs of regular universal childhood vaccines (e.g. un-safety/fear of adverse events, non-severity of the disease, lack of information about risk of vaccination) were similar to those among the general population in various countries during the A(H1N1) pandemic [62, 63] as well as for routine universal vaccinations [46, 64‐72]. The same factors were also found on many anti-vaccination websites [73‐76] opposing routine universal vaccination. New forms of reluctance to vaccinate seem to emerge in the general population, identified as people following an alternative dietary system (macrobiotic) and among so called critical citizens [77, 78]. Another phenomenon are the free-riders: in a highly vaccinated population one can avoid vaccine adverse events by non-vaccination while being protected by the vaccinated contacts (herd immunity) [79]. If free-riding takes hold in a social network new under-vaccinated pockets may arise. As these new opponents are (as yet) not organised as a group as defined in this article, we did not include them in the literature review. However, we are aware that these “like-minded groups that are not geographically clustered” might gain importance in the near future as the number of followers seems to be growing. It is therefore important to start engaging with these “like-minded groups that are not geographically clustered” as soon as possible by listening to their arguments and try to mitigate vaccine refusals.

In our opinion, two shared beliefs for non-vaccination, also found in the general population, are amenable for influencing vaccination decisions by targeted communication tactics that are discussed later on: perceived non-severity of the disease and its possible complications, and vaccine un-safety. The factors for non-vaccination for Irish Travellers and Roma communities are different and seem to be related mostly to access to health care and therefore also other interventions than communication are needed.

An important limitation of these two literature reviews is that we limited the search to English language peer-reviewed literature. A lot of knowledge is actually available in the grey literature and in the countries where the UVGs live, as it is the case in the Netherlands for Orthodox Protestants, and in Portugal for Roma [80]. However, this information is not available in the open English language scientific literature. Another limitation is that we restricted the search to vaccination and immunisation in MeSH and title and/or abstract. Vaccination is part of the process of health in general and beliefs and attitudes are closely linked. Therefore, we did not include articles explaining beliefs and attitudes regarding vaccination in the broad framework of health. For example, health-related beliefs for Roma and Irish Travelers communities are well described in many articles [81‐84] but the relation to vaccination seems to be less important, as access to health care is the dominant factor in these groups.

Previous work in the UK suggests that indiscriminate population-based interventions, that aim to improve overall uptake of vaccination, are unlikely to reduce social-based inequalities in uptake [85]. There needs to be recognition of the differences between population groups, that different approaches are essential to meet the needs of these groups, and that a specific effort has to be made to reach groups with barriers to vaccination in routine vaccination programmes [85, 86]. We have found that important (changeable) beliefs for non-vaccination are shared by many groups, as well as by the general population. We therefore argue that in developing communication strategies for specific UVGs and the general public, partly the same arguments may be used. However, to reach UVGs it is important to co-operate with these groups and to adapt the information to their specific needs. If used in a trustworthy and reliable context, UVGs can use the information, also from other members in their group who do vaccinate, for deciding on vaccination. Several technical reports and tools were developed by ECDC and WHO for health care professionals and Public Health Institutes to increase vaccination uptake and suggest communications activities such as educating people about risks of vaccinating and not vaccinating, addressing misconceptions, promote positive health outcomes, and partnering with health care workers as they are believed to be a trusted source. These tools target especially MMR [87, 88] and/or the general population [89]. A study by Horne et al., 2015 [90] with commentaries by Betsch et al. 2015 [91] and Horne et al. 2015 [92] have shown that highlighting objective information about the consequences of not vaccinating and countering vaccination myths can positively impact the intention to vaccination of people who are doubting. However, on the other hand Nyhan et al., 2014 [93] showed that attempts to increase concerns about communicable diseases (e.g. fear appeals and narratives) or correct false claims about vaccines may be in some cases counterproductive. It is therefore important to carefully test vaccination messages in a specific group.

Governments and public health authorities might have to take a different stand regarding UVGs: firstly, they could act as sentinel population for early detection of transmission of VPD as the large number of susceptibles increases the chance of disease detection if transmission occurs, secondly, they might also be used as well as sentinel for beliefs/attitudes and reasons for non-vaccination in the general population as some of them might take over similar ideas about vaccination. Therefore, efforts to communicate with these groups should start as soon as possible in all EU-countries. The epitheton “hard-to-reach” should be abandoned, as not all groups are hard-to-reach and each group has its specific reasons and even individuals with in a group may differ for which specific approaches are needed and not general ones. Better that each country determines its own UVGs with their own beliefs and starts to develop trustful relationships.

Within each UVG identified, there are a variety of health beliefs and objections to vaccination. In addition, similar factors are shared by several of these groups. Communication strategies regarding these similar factors such as educating people about the risks associated with being vaccinated versus not being vaccinated, addressing their concerns, and countering vaccination myths present among members of a specific UVG through a trusted source, can establish a reliable relationship with these groups and increase their vaccination uptake. Furthermore, other interventions such as improving access to health care could certainly increase vaccination uptake in Roma and Irish travellers.