Combining an Effective Rule-based Chatbot With ChatGPT-supported Real-time Question-answer Functions to Promote Seasonal Influenza Vaccination Among Community-dwelling People Aged 65 Years and Above

Combining an Effective Rule-based Chatbot With ChatGPT-supported Real-time Question-answer Functions to Promote Seasonal Influenza Vaccination Among Community-dwelling People Aged 65 Years and Above: a Partially Blinded Randomized Controlled Trial

This study is a partially blinded (outcome assessors and data analysts) and parallel-group randomized controlled trial. Community-dwelling people aged ≥65 years who have not received the SIV for the approaching flu season will be randomized evenly (1:1) into either the intervention group or the control group. During the intervention period, the intervention group will have access to the hybrid combination of a rule-based chatbot (SIV-Chatbot) with the ChatGPT-supported real-time Question & Answer (QA) functions, while the control group will have access only to the SIV-Chatbot.

The SIV-Chatbot will deliver the same interventions for both groups. The number of intervention sessions (four) and timing (week 0, 2, 4 & 6) will also be the same. In the intervention group, the hybrid Chatbot will invite the participants to raise open-ended questions related to SIV using flexible methods (such as voice messages, typing with keyboards, or handwriting) at each session. The ChatGPT will answer these questions immediately in the format of text messages. The functions can be used repeatedly throughout the intervention period (weeks 0-6), and participants will be free to spend as much time as they want on such functions.

Telephone interviews will be conducted at baseline (T0), after completion of the intervention (T1), and six months after T1 (T2). The primary outcome will be the self-reported SIV uptake measured at T2. The research team will validate that outcome by requesting the participants upload an image of their SIV receipt, while hiding their personal identification, via the WhatsApp account used in this study.

Study Overview

• Status: Not yet recruiting
• Conditions: Vaccination Promotion
• Intervention / Treatment: Behavioral: Hybrid chatbot; Behavioral: Rule-based chatbot

• Study Type: Interventional
• Enrollment (Estimated): 454
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Zixin Wang, PhD; Phone Number: +852 22528474; Email: wangzx@cuhk.edu.hk

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 65 years and older (Older Adult)
• Accepts Healthy Volunteers: Yes
• Genders Eligible for Study: All

Description

Inclusion Criteria:

• aged ≥65 years
• possession of a Hong Kong ID
• able to speak and comprehend Cantonese
• have a smartphone with internet access
• have either installed or are willing to install WhatsApp on their smartphone
• have not taken seasonal influenza vaccination for the approaching flu season

Exclusion Criteria:

• score ≤16 in the validated telephone version of the Cantonese Mini-Mental State Examination (T-CMMSE)
• either blindness or deafness
• with known contraindications to the SIV as indicated by the Hong Kong Centre for Health Protection (e.g., history of severe allergic reactions to any of the vaccine component or a previous dose of SIV and bleeding disorders)

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Health Services Research
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Single

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Intervention group; Have access to the hybrid combination of a rule-based chatbot (SIV-Chatbot) with the ChatGPT-supported real-time QA functions	Behavioral: Hybrid chatbot; After assessing participants' stage of change (SOC) regarding SIV uptake, the rule-based component (SIV-Chatbot) will deliver online interventions tailored to their current SOC. There will be four intervention sessions at week 0, 2, 4 and 6. In addition, the hybrid Chatbot will invite the participants to raise open-ended questions related to SIV using flexible methods at each session. The ChatGPT will answer these questions immediately in the format of text messages. The functions can be used repeatedly throughout the intervention period (weeks 0-6), and participants will be free to spend as much time as they want on such functions.
Active Comparator: Control group; Have access only to a rule-based chatbot (SIV-Chatbot)	Behavioral: Rule-based chatbot; After assessing participants' stage of change (SOC) regarding SIV uptake, the rule-based chatbot (SIV-Chatbot) will deliver online interventions tailored to their current SOC. There will be four intervention sessions at week 0, 2, 4 and 6.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Uptake of seasonal influenza vaccination	The primary outcome will be the self-reported seasonal influenza vaccination uptake measured at T2 (six months after completion of the intervention). The research team will validate that outcome by requesting the participants upload an image of their receipt.	Six months after completion of the intervention

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Stage of change related to seasonal influenza vaccination uptake	Participants' SOC will be measured at T0 (baseline), T1 (after completion of intervention), and T2 (six months after completion of the intervention) by using validated questions	T0 (baseline), T1 (after completion of intervention), and T2 (six months after completion of the intervention)
Knowledge and attitudes related to seasonal influenza vaccination	Knowledge and attitudes will be measured at T0 (baseline) and T2 (6 months after completion of the intervention) by validated tools	T0 (baseline) and T2 (6 months after completion of the intervention)

Collaborators and Investigators

• Sponsor: Chinese University of Hong Kong

Study record dates

Study Major Dates

• Study Start (Estimated): November 16, 2026
• Primary Completion (Estimated): December 31, 2027
• Study Completion (Estimated): December 31, 2027

Study Registration Dates

• First Submitted: November 8, 2026
• First Submitted That Met QC Criteria: November 8, 2026
• First Posted (Actual): November 13, 2026

Study Record Updates

• Last Update Posted (Actual): November 13, 2026
• Last Update Submitted That Met QC Criteria: November 8, 2026
• Last Verified: November 1, 2026

More Information

Terms related to this study

• Other Study ID Numbers: GRF14611325

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

IPD Plan Description

The data presented in this study are available from the corresponding author upon request. The data are not publicly available as they contain sensitive personal information.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No