Despite the strong health-promotion efforts of Sierra Leone’s Ministry of Health and Sanitation (MoSH), Covid-19 vaccine demand in the country lags behind supply, largely due to concerns about side effects. To increase demand for Covid-19 and other vaccines, this research team is partnering with MoSH and UNICEF to investigate whether leveraging connections in WhatsApp and in-person social networks can encourage vaccination. Researchers will recruit partially vaccinated and unvaccinated individuals in Freetown and collect information on their WhatsApp and in-person network contacts, to assess the impact of their information-sharing behavior. Participants will randomly receive various evidence-informed interventions, including differing incentives to promote vaccination among their contacts and information- and vaccine-literacy training. Researchers will then measure vaccine uptake and information literacy among participants and their networks, with an aim to establish the most effective means of encouraging social learning to promote vaccination, use of essential health services, and skills to identify misinformation.