Understanding the factors associated with vaccine scepticism is challenging because of the 'small-pockets' problem: The number of highly vaccine-sceptical people is low, and small subsamples such as these can be missed using traditional regression approaches. To overcome this problem, the current study (N = 5,200) used latent profile analysis to uncover six profiles, including two micro-communities of vaccine-sceptical people who have the potential to jeopardize vaccine-led herd immunity. The most vaccine-sceptical group (1.14%) was highly educated and expressed strong liberal tendencies. This group was also the most sceptical about genetically modified crops and nuclear energy, and most likely to receive news about science from the Internet. The second-most vaccinesceptical group (3.4%) was young, poorly educated, and politically extreme (both left and right). In resolving the small-pockets problem, the current analyses also help reconcile competing theoretical perspectives about the role of education and political ideology in shaping anti-vaccination views.Vaccines are one of the most effective population health interventions in history (Ehreth, 2003;Plotkin, 2014). Unsurprisingly, then, the majority of the public views vaccines positively (Larson, de Figueiredo, Karafillakis, & Rawal, 2018). However, it only takes a small proportion of the population to not vaccinate to undermine herd immunity and trigger public health crises. This is why anti-vaccination movements arouse so much concern, even though there are relatively few anti-vaccination advocates. Indeed, in 2019 the World Health Organization listed vaccine hesitancy as one of the top 10 threats to global health in 2019 (WHO, 2019). This urgency has intensified since, as evidence mounts of fear and resistance towards COVID-19 vaccines (Rigby, 2020;Roozenbeek et al., 2020).Gaining a nuanced, quantitative understanding of the factors associated with antivaccination attitudes is challenging because of what we refer to here as the 'small-pockets' problem: The number of people with strong anti-vaccination attitudes represents a small