CI

At a glance

ClinicalIndex Comparison Record
N/ACompleted· 930 enrolled
Drug / intervention
Default-style LLM chatbot +2 morebehavioral
Likely dose
Not stated in record
Structured eligibility isn't available for this trial yet — see the full criteria in the Eligibility tab below.

Standardized by ClinicalIndex from the ClinicalTrials.gov record · verify against the source.

Search/NCT07132125
NCT07132125N/ACompleted

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

University of Pennsylvania·interventional·Posted Aug 20, 2025·Updated Aug 20, 2025

In Brief

A clinical study evaluating Default-style LLM chatbot, Conversational-style LLM chatbot, and 1 other intervention for HPV Vaccination Intent. Completed, enrolled 930 participants across 1 site.

Detailed Summary

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 Details

Study Typeinterventional
Allocation--
Masking--
Primary Purpose--
CountriesUnited States
Collaborators--

Timeline

N/ACompletedFinished
2026
First PostedAug 20, 2025
Enrollment StartMar 17, 2025
Primary CompletionMay 22, 2025
TodayJul 2, 2026
Enrollment to primary: 2 monthsPosted 10 months ago

Interventions

Default-style LLM chatbotbehavioral

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.