How to leverage social media to build confidence in COVID-19 vaccines: findings and lessons learned from nationwide campaigns in four countries.

Vaccine hesitancy remains a global health challenge, undermining gains in routine immunization coverage and the uptake of COVID-19 vaccines worldwide. Effective, responsive health communication is needed to counter 'infodemics' and strengthen public trust in vaccination. Evidence on how to design effective digital campaigns to strengthen vaccine demand is limited, particularly in low- and middle-income countries. Results from this four-country study demonstrate a process for the design and randomized controlled testing of evidence-based, context-driven persuasive messaging to strengthen vaccine demand. Campaigns led to 3.5 M+ clicks to additional resources, and messages were successful at shifting attitudes toward vaccine confidence, with campaigns in local languages performing better in encouraging information-seeking behavior (clickthrough rate). Strategic partnership with UNICEF country offices was key to convert behavioral insights into effective communication strategies. This work provides a replicable process that local health agencies can adopt to strengthen their digital social and behavior change communications.