The COVID-19 pandemic is bringing about far-reaching structural changes on both the economy and public health, and conventional methodologies have to be fine-tuned to assist public health decision making. In this context, behavioural economics, which is situated at the crossroads between economics and social psychology, is an undeniably innovative field. In contrast with conventional models, the economic models of behavioural economics incorporate psychological and social determinants to produce more accurate predictions of individual behaviour. In the last 20 years, the scientific community has been using this approach's quantitative tool, experimental economics, in many areas of health, including prevention, promotion, human resources and social signage. Studies have come up with effective solutions that have improved best public health practices and provided sources of inspiration that should not be overlooked in the fight against COVID-19. They have allowed natural human behaviour to take a central role again, helped us to understand how the social and economic environment influences individuals, and enabled us to anticipate human reactions and so make faster adjustments to public policies.