Information nudging, attitude, and protective behaviours against Nipah virus in India, 2026: a national experimental survey

Background: Nipah virus (NiV) poses a significant public health threat due to its high fatality, yet public readiness for medical countermeasures remains understudied. We aimed to evaluate the associations of perceived severity and benefits information nudges with the dimensions of the Health Belief Model (HBM), identify highly responsive populations, and assess whether changes in HBM dimensions mediate the associations between information nudges and protective behavioural intentions in India. Methods: We conducted a nationwide experimental web survey among Indian adults between 6 and 18 February 2026. The survey contained an embedded information nudge module in which participants were randomly assigned to one of three groups: a perceived severity nudge, a perceived benefits nudge, or no nudge. We assessed changes in HBM dimensions using analysis of covariance. Six predictive models were evaluated to identify subpopulations highly susceptible to cognitive shifts. Mediation analyses were performed to estimate the indirect effects of nudges on intentions to promptly seek medical care, receive vaccination, and accept treatment. Results: Our sample comprised 1,124 participants randomly assigned to receive a perceived severity nudge (n = 373), a perceived benefits nudge (n = 376), or no nudge (n = 375). Compared with no nudge, the severity nudge significantly increased perceived severity (adjusted mean difference (AMD) = 0.17; 95% confidence interval (CI) = 0.05, 0.30; P = 0.005) and cues to action (AMD = 0.20; 95% CI = 0.09, 0.32; P < 0.001), while the benefits nudge significantly increased cues to action (0.30; 95% CI = 0.19, 0.41; P < 0.001). Predictive modelling (extreme gradient boosting: area under the receiver operating characteristic curve (AUROC) = 0.717; logistic regression: AUROC = 0.789) identified baseline health beliefs and residence outside prior outbreak regions as dominant contributors to nudge responsiveness. Mediation analyses indicated significant indirect effects of the severity nudge on treatment intention via perceived severity (effect estimate (β) = 0.016; 95% CI = 0.002, 0.032), as well as the perceived benefits nudge via cues to action on both vaccination intention (β = 0.024; 95% CI = 0.001, 0.054) and treatment intention (β = 0.028; 95% CI = 0.002, 0.055). Neither information nudge significantly influenced promptly seeking medical care. Conclusions: Targeted information nudges could alter health beliefs and influence vaccination and treatment readiness through distinct psychological pathways.