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This multi-country trial evaluates an AI chatbot designed to counter cognitive biases and inoculate parents against vaccine misinformation, embedded within a large survey across five European countries (n=5,000). Scaled from a 2026 single-country study, outcomes compare behavioural and attitudinal responses against standard-of-care materials (e.g., UNICEF infographics) to identify effective, scalable misinformation interventions.
The aim of this multi-country trial is to identify and quantify the effectiveness of inoculation strategies against vaccine-related misinformation. Building on a single-country study implemented in early 2026 [NCT07488962], the study evaluates an AI chatbot designed to counter cognitive biases, embedded within a larger survey to enable integrated assessment of engagement, behavioural responses, and system performance at scale.
The study will be conducted across five European countries-the United Kingdom, the Netherlands, Croatia, Latvia, and Slovakia-with a total sample of 5,000 parents or caregivers (n=1,000 per country). Participants will complete a structured survey assessing childhood vaccination behaviours, vaccine confidence, trust in information sources, exposure to misinformation, and relevant psychological and sociodemographic factors.
Participants will be randomly assigned to either the intervention or control arm. The intervention arm will receive the AI-based chatbot, while the control arm will receive standard-of-care materials-such as national or international health institute communications (e.g., UNICEF infographics)-that address the same misinformation messages, enabling a direct and rigorous comparison.
The primary outcome is parents' ability to correctly distinguish true from false childhood vaccine statements. Quantitative analyses will include pooled and country-specific models to identify determinants of vaccine confidence and estimate intervention effects. Findings will clarify drivers of declining vaccine confidence and assess whether a scalable AI-based chatbot can reduce vulnerability to misinformation and support informed vaccination decisions.
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| Label | Type | Description | Intervention Names |
|---|---|---|---|
| AI-driven chatbot | Experimental | An interactive, web-based, AI-driven chatbot intervention designed to counter vaccine misinformation. It can be accessed via a personal computer, tablet, or mobile device through a web- browser link. |
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| Social media infographic | Active Comparator | A UNICEF social media infographic with three "myth vs. fact" statements on vaccination that correspond to the same misinformation tactics explained by the MindShield chatbot. |
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| Name | Type | Description | Arm Group Labels | Other Names |
|---|---|---|---|---|
| AI-driven chatbot | Behavioral | A tailored AI-driven chatbot designed to counter vaccine misinformation. |
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| Measure | Description | Time Frame |
|---|---|---|
| Parental susceptibility to misinformation about childhood vaccination | The primary outcome of this study will assess parental susceptibility to misinformation about childhood vaccination, defined as parents' ability to accurately distinguish between true and false vaccine-related information. This will be measured using ten statements on childhood vaccines, including four true and six false, rumour-related statements. Two of the rumour-related statements correspond to each of the three misinformation tactics introduced by the chatbot and the UNICEF infographic. This measure reflects parents' ability to identify misinformation containing manipulation tactics they were inoculated against and to distinguish true from false information regarding childhood vaccination. Responses will be recorded as "True", "False", or "Don't know". A composite misinformation susceptibility score will be calculated based on the number of correct responses, with higher scores indicating greater ability to identify vaccine misinformation accurately. | Through study completion, an average of 20-30 minutes |
| Measure | Description | Time Frame |
|---|---|---|
| Self-efficacy | Participants' self-efficacy will be evaluated in two domains: (a) confidence in making informed vaccination decisions for their children, measured with a binary response of "Yes" or "No", and (b) confidence in seeking trustworthy information about childhood vaccinations, measured on a four-point scale from "Not at all confident" to "Very confident". | Through study completion, an average of 20-30 minutes |
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Inclusion Criteria:
Exclusion Criteria:
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| Name | Role | Phone | Extension | |
|---|---|---|---|---|
| Leesa Lin, PhD | Contact | +44 (0)20 7636 8636 | Leesa.Lin@lshtm.ac.uk | |
| Kana Kobayashi, MSPH | Contact | Kana.Kobayashi@lshtm.ac.uk |
| Name | Affiliation | Role |
|---|---|---|
| Leesa Lin, PhD | London School of Hygiene and Tropical Medicine | Principal Investigator |
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| Social media infographic | Behavioral | A UNICEF social media infographic with three "myth vs. fact" statements on vaccination. |
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