Vaccine voices in the digital sphere: a multilayer network analysis of online forum discussion in Taiwan

New spatiotemporal considerations of the network allow surveillance of vaccine opinion online. The study uses a multilayer network – with each layer representing vaccine opinion discussion – to examine how the structure and timing of engagement in online communities may affect the spread of COVID-19 vaccine opinions. The aim is to improve public health messaging management during health crises and contribute to WHO’s growing infodemic research agenda. The study finds that online discussions on COVID-19 vaccines are dominated by a few highly connected nodes within power-law structured communities. Vaccine-hesitant and pro-vaccine discussions are more engaged with, and more frequently posted earlier, but overall, less densely connected than the fewer, but highly clustered anti-vaccine discussions. Temporally, this trend increases over time for anti-vaccine discussions, suggesting insular communication (and potential echo chambering) happens gradually. The findings suggest proactive information management with consistent vaccine advocacy in online communities is crucial in low-activity periods, as dense anti-vaccination networks may pose misinformation risks.