What nudges you to take a vaccine? Understanding behavioural drivers of COVID-19 vaccinations using large-scale experiments in the G-7 countries.

Introduction: We present a unique multi-country, two-wave dataset of 42,417 survey responses drawn from nationally representative samples of citizens from the G-7 countries: Canada, France, Germany, Italy, Japan, UK, and USA. This data note outlines the motivation and methodology of the survey instrument and describes the measures contained in the dataset. We highlight areas for future research.

Methods: We fielded an online survey over two waves (January 27 to February 26 [n = 24,303] and wave 2 from March 6 to May 12 [n = 18,114]) measuring a range of demographic, social, political, and psychological variables. Samples were nationally representative by age, education, gender, and subnational region. Each wave included of three experiments (one conjoint and two between-subjects) to facilitate randomised evaluation of behavioural health policies promoting the uptake of COVID-19 booster vaccinations.

Results: The dataset has produced two peer-reviewed publications at the time of writing ([Banerjee, S., John, P., Nyhan, B., Hunter, A., Koenig, R., Lee-Whiting, B., Loewen, P. J., McAndrews, J., & Savani, M. M. (2024). Thinking about default enrollment lowers vaccination intentions and public support in G7 countries. PNAS Nexus, 3(4), pgae093]; [Koenig, R., Savani, M. M., Lee-Whiting, B., McAndrews, J., Banerjee, S., Hunter, A., John, P., Loewen, P. J., & Nyhan, B. (2024). Public support for more stringent vaccine policies increases with vaccine effectiveness. Scientific Reports, 14(1), 1748]). A summary report is posted online (https://www.thebritishacademy.ac.uk/publications/overcoming-barriers-to-vaccination-by-empowering-citizens-to-make-deliberate-choices/). Additional research outputs are currently under preparation.

Discussion: Our dataset combines observational and experimental data on behavioural health policies, offering numerous insights. First, the dataset's extensive size and geographical diversity enables comparative analysis of public health issues involving social, political, and behavioural factors. Second, the dataset is suited to advanced statistical methods that can explore heterogeneity in the uptake of behavioural health policies, such as vaccine nudges. Third, the timing of the data collection, coinciding with the rise of the Omicron variant, provides valuable insights into why some previously vaccinated individuals might hesitate to receive additional doses, potentially improving our understanding of the COVID-19 pandemic and possible responses to pandemics and other public health emergencies in the future.