Vaccine Perceptions in online informal milk-sharing networks: implications for public health

Abstract Background COVID-19 changed vaccination perceptions and trust in health recommendations. Social media milk-sharing networks provide insights into parental vaccine concerns and their public health impact. Methods Reflexive thematic analysis was conducted on data from public Facebook groups for informal human milk-sharing in Israel (10.1K members) and the UK (7.3K members) from 2021-2024. Donor COVID-19 vaccination status narratives and recipient preferences were analyzed to identify main themes. Findings We recognized frequent references to COVID-19 vaccination status in both groups, highlighting two main themes: 1. Disclosure of Vaccination Status - Donors in both countries consistently shared their COVID-19 vaccination status when offering human milk. The majority explicitly stated they were fully or partially vaccinated, following national health guidelines. 2. Preference for Non-vaccinated Donor - Recipients have a clear and ongoing preference for milk from unvaccinated donors. This preference persisted consistently throughout the study period in the UK. This preference was also initially evident in Israel but became less pronounced over time. Conclusions Our findings reveal clear patterns in vaccination perceptions among informal human milk-sharing participants. Donors consistently disclosed vaccination status, aligning with institutional recommendations. Recipients, however, showed a persistent preference for milk from unvaccinated donors, reflecting vaccine-related concerns. Public health interventions should address vaccination concerns within milk-sharing social media communities to build trust and reduce vaccine hesitancy. This mistrust may extend to routine vaccinations, presenting broader consequences for public health. Key messages • Recipient preference for unvaccinated milk highlights ongoing vaccine skepticism. • Public health communication must address vaccine hesitancy explicitly to build trust.