Let's call! Using the phone to increase vaccine acceptance.

In the context of the COVID-19 pandemic, we develop and test experimentally three phone-based interventions to increase vaccine acceptance in Mozambique. The first endorses the vaccine with a simple positive message. The second adds the activation of social memory on the country's success in eradicating wild polio with vaccination campaigns. The third further adds a structured interaction with the participant to develop a critical view toward misleading information and minimize the sharing of fake news. We find that combining the endorsement with the stimulation of social memory and the structured interaction increases vaccine acceptance and trust in institutions.