Although vaccination uptake is high in most countries, pockets of sub-optimal coverage remain posing a threat to individual and population immunity. Increasingly, the term 'vaccine hesitancy' is being used by experts and commentators to explain sub-optimal vaccination coverage. We contend that using this term to explain all partial or non-immunisation risks generating solutions that are a poor match for the problem in a particular community or population. We propose more precision in the term 'vaccine hesitancy' is needed particularly since much under-vaccination arises from factors related to access or pragmatics. Only with clear terminology can we begin to understand where the problem lies, measure it accurately and develop appropriate interventions. This will ensure that our interventions have the best chance of success to make vaccines available to those who want them and in helping those who are uncertain about their vaccination decision.