Conversations With AI Chatbots Increase Short-Term Vaccine Intentions But Do Not Outperform Standard Public Health Messaging

University of Pennsylvania930 enrolled

Overview

The goal of this clinical trial is to test whether short conversations with large language model (LLM) chatbots can persuade vaccine-hesitant parents to vaccinate their children against human papillomavirus (HPV). The study compares two chatbot styles to official public health information and to a no-message control. Parents of HPV-eligible children first complete a survey about their attitudes toward the HPV vaccine and their main concerns. They are then randomly assigned to read public health materials, have a three-minute conversation with either a default-style chatbot or a conversational-style chatbot tailored to their concern, or receive no message. The main outcome is change in intent to vaccinate immediately after the intervention, with follow-up surveys at 15 and 45 days.

Study Type

INTERVENTIONAL

Allocation

RANDOMIZED

Purpose

PREVENTION

Masking

NONE

Enrollment

930

Conditions

HPV Vaccination Intent

Interventions

A large language model chatbot (GPT-4o) that delivers tailored persuasive messages to parents about HPV vaccination, using the model's default style with longer, structured responses. Participants engage in a three-minute, multi-turn conversation, with responses personalized to their top-rated vaccine concern identified in a pre-intervention survey.

Conversational-style LLM chatbotBEHAVIORAL

A large language model chatbot (GPT-4o) that delivers tailored persuasive messages to parents about HPV vaccination in a conversational style, with short responses. Participants engage in a three-minute, multi-turn conversation, with responses personalized to their top-rated vaccine concern identified in a pre-intervention survey.

Public health informational materialsBEHAVIORAL

Official public health informational materials on HPV vaccination from the Centers for Disease Control and Prevention (U.S.), National Health Service (U.K.), or Public Health Agency of Canada, matched to the participant's country of residence. Materials are 589-680 words in length, cover HPV risks and benefits of vaccination, and are presented for three minutes before participants proceed.

Eligibility

Sex: ALLMin age: 18 YearsHealthy volunteers:

Medical Language ↔ Plain English

Inclusion Criteria: * Adults aged 18 years and up * Living in Canada, the UK, or the USA * At least one child eligible for HPV vaccine based on country-specific guidelines who has not received any doses of the vaccine or whose vaccination status is unknown Exclusion Criteria: * Failure to pass attention checks * Identified as non-human respondents by reCAPTCHA or other automated bot detection

Outcomes

Primary Outcomes

Change in intent to vaccinate child against HPV within the next 12 months

Self-reported likelihood, on a 0-100 scale, of vaccinating the participant's youngest HPV vaccine-eligible child (identified in pre-survey) within the next 12 months. Measured before and immediately after the intervention to assess short-term changes in vaccination intent.

Time frame: Baseline to immediately post-intervention

Secondary Outcomes

Change in intent to vaccinate child against HPV at 15-day follow-up

Self-reported likelihood, on a 0-100 scale, of vaccinating the participant's youngest HPV vaccine-eligible child within the next 12 months. Measured at baseline and 15 days after the intervention to assess durability of effects.

Time frame: Baseline to 15 days post-intervention

Change in intent to vaccinate child against HPV at 45-day follow-up

Self-reported likelihood, on a 0-100 scale, of vaccinating the participant's youngest HPV vaccine-eligible child within the next 12 months. Measured at baseline and 45 days after the intervention to assess durability of effects.

Time frame: Baseline to 45 days post-intervention

Change in general parental vaccine hesitancy (PACV-5)

Change in scores on the 5-item Parent Attitudes about Childhood Vaccines (PACV-5) scale. Measured at baseline and immediately after the intervention.

Time frame: Baseline to immediately post-intervention

Change in intent to vaccinate child for influenza and COVID-19

Self-reported likelihood, on a 0-100 scale, of vaccinating the participant's youngest eligible child for influenza or COVID-19 within the next 12 months.

Time frame: Measured at baseline and immediately post-intervention.

Change in importance ratings of HPV vaccine concerns

Change in participant ratings (0-100 scale) of importance for each HPV vaccine concern (list derived from National Immunization Surveys) between baseline and immediately post-intervention.

Time frame: Baseline to immediately post-intervention

Clicks on HPV vaccine appointment scheduling link

Whether participants click a provided link to schedule an HPV vaccine appointment through CVS during the post-intervention survey.

Time frame: Immediately post-intervention

Willingness to donate payment to vaccine education charity

Percentage of survey payment participants choose to donate (0%, 10%, 30%, or 50%) to an immunization-related charity during the post-intervention survey.

Time frame: Immediately post-intervention

Willingness to be recontacted for future research

Participant self-reported willingness (yes/no) to be contacted for future studies

Time frame: Immediately post-intervention

Ratings of empathy, usefulness, and relevance of intervention content

Participant ratings (1-5 scale) of how empathetic, useful, and relevant they found the assigned chatbot conversation or public health reading material.

Time frame: Immediately post-intervention

Conversations With AI Chatbots Increase Short-Term Vaccine Intentions But Do Not Outperform Standard Public Health Messaging

Overview

Conditions

Interventions

Eligibility

Locations (1)

Outcomes

Primary Outcomes

Secondary Outcomes