Conspiracy beliefs and vaccination readiness among Japanese healthcare workers: A nationwide cross-sectional study (JACSIS 2024–2025)

Conspiracy beliefs have consistently been linked to vaccine hesitancy, yet evidence among Japanese healthcare workers (HCWs) remains limited. We analyzed data from the Japan COVID-19 Society Internet Survey (December 2024–January 2025). Conspiracy beliefs were measured using a 10-item composite (seven-item Vaccine Conspiracy Beliefs Scale plus three Oxford Coronavirus Explanations, Attitudes, and Narratives Survey items; 5-point response options). Vaccination readiness was assessed using the 7C scale; to minimize conceptual overlap with the exposure, our primary outcome was the modified 6C score excluding the conspiracy subscale. We compared conspiracy belief distributions between HCWs and non-HCWs and fitted multivariable regression models among HCWs. Of 25,082 respondents (mean age 49.8 years; 49.9% men), 3.9% were HCWs. Non-HCWs reported higher endorsement on six of 10 conspiracy items related to vaccine safety and efficacy (all p < 0.05). Among HCWs ( n = 982), higher conspiracy beliefs were associated with lower vaccination readiness in adjusted models (6C: B = −0.368, p < 0.001). Results using the original 7C overall score were similar. In analyses using COVID-19 vaccination uptake during April–September 2024 as a behavioral outcome, high conspiracy beliefs were not significantly associated with uptake, although confidence intervals were wide. In this nationwide sample, conspiracy beliefs were inversely associated with HCWs' vaccination readiness, while demographic and socioeconomic covariates contributed relatively little. Given the exploratory cross-sectional design, these findings are correlational and should be considered hypothesis-generating. Future longitudinal and interventional studies should evaluate whether addressing misinformation-related beliefs can improve vaccination-related outcomes among HCWs. • This study investigates vaccine conspiracy beliefs among healthcare workers (HCWs). • Participants were 25,082 respondents from the 2024–2025 JACSIS survey. • Higher conspiracy belief scores in HCWs were linked to lower vaccination readiness. • Findings highlight need for targeted strategies to boost vaccine confidence.