This latter study is particularly important in the context o

This latter study is particularly important in the context of vaccine refusal, since it supports a growing body of research which underscores the role of clusters of non-vaccinators in lowering herd immunity and allowing for disease outbreaks (Salathé and Bonhoeffer, 2008; Liu et al., 2015). The US Centers for Disease Control have also recognized this phenomenon, highlighting also the vulnerability of under-vaccinated groups to imported diseases, and noting a paradigm-shift away from access as the primary barrier to vaccinations and towards “philosophical objections” (CDC, 2013). It is thus worth stressing the importance of monitoring performance in UNC2025 programmes (de Figueiredo et al., 2016) and identifying and monitoring hesitant groups: small clusters of non-vaccinators can have disproportionately adverse effects on herd immunity and epidemic spread. Our objectives in this paper are to: respond to international calls for monitoring public confidence in immunization; examine worldwide variation in attitudes, exploring the socio-economic determinants of vaccine attitudes; and, finally, interpret and discuss the results in the context of global immunization and monitoring systems. This study – in collaboration with WIN/Gallup International Association – draws from the ten-question Likert survey proposed by SAGE (Larson et al., 2015a, 2015b) and comprises survey responses from 65,819 individuals across 67 countries to questions on vaccination importance, safety, effectiveness, and religious compatibility. This study builds on a five-country vaccine confidence survey conducted in collaboration with Win/Gallup International in 2014 (Larson et al., 2014a, 2014b). We believe this study to be of unprecedented scale in the vaccine confidence literature, and a potential cornerstone for monitoring of public confidence in immunization. We begin by exploring worldwide variation in attitudes to four statements investigating individuals\' perceptions of the importance, safety, and effectiveness of vaccines, as well as the compatibility with their religious beliefs. We then highlight regional trends in vaccine safety perceptions and explore socio-economic determinants of vaccine sentiments using logistic hierarchical modelling.
Methods
Results Immunization-response data is renormalized after removing “do not know/no response” responses. An overall summary by question and country (stratified by world region as defined by the World Health Organization) is shown in Fig. 1 using weighted responses, which are adjustments to account for over- or under-represented individuals within the population. (World regions are categorized by WHO region according to the definitions at www.who.int/about/regions/en (accessed 08/07/2016): AFR (Africa region); AMR (Americas region); EMR (Eastern Mediterranean region); EUR (European region); SEAR (South-East Asia region); and WPR (Western Pacific region).) Overall differences in responses between the six WHO regions are again shown as Likert responses in Fig. 2a and worldwide vaccine attitudes to vaccine safety are mapped in Fig. 2c (South, 2011). Variability in vaccine sentiment across countries and WHO regions is investigated by considering the fraction of respondents who either agree or disagree with the four statements on immunization (Fig. 1). The EUR region reports the highest mean-averaged (across all countries in the region) negative responses for vaccine importance, safety, and effectiveness (8.0%, 17.0%, and 11.3%, respectively) and seven of the ten most negatively-reporting countries to vaccine safety are in EUR. Pairwise t-tests between regional means demonstrate that EUR has more importance- and safety-related skepticism than AFR, AMR, EMR, and SEAR (at p=0.05), and that WPR has more safety-related skepticism than SEAR. EUR has more effectiveness-related skepticism than AMR. SEAR and WPR report the most religious incompatibility (25.7% and 24.3% respectively): pairwise t-tests reveal significance at p=0.05 between these two regions and the four others, but none between them.