Chatbot-delivered Theory-based Online Intervention in Increasing Seasonal Influenza Vaccination Uptake Among Children Aged 3-6 Years

A Randomized Controlled Trial Evaluating a Chatbot-delivered Theory-based Online Intervention in Increasing Seasonal Influenza Vaccination Uptake Among Children Aged 3-6 Years

This randomized controlled trial will compare the efficacy of a Chatbot-delivered stage-of-change-tailored online intervention versus a Chatbot-delivered non-stage-of-change-tailored online intervention for mothers in increasing seasonal influenza vaccination uptake of their children aged 3-6 years. Mothers of children aged 3-6 years will be randomized evenly into either the intervention or the control group.

In the intervention group, the Chatbot will assess mothers' stage of change regarding their children's seasonal influenza vaccination uptake and deliver SOC-tailored interventions through WhatsApp every two weeks for four times.

In the control group, the Chatbot will provide a standard and non-stage-of-change-tailored intervention every two weeks for four times.

All participants will complete three telephone surveys at baseline (T0), after completion of the intervention (T1) and three months after T1 (T2).

Study Overview

• Status: Not yet recruiting
• Conditions: Behavior Change
• Intervention / Treatment: Behavioral: Stage-of-change-tailored intervention; Behavioral: Non-stage-of-change-tailored intervention

• Study Type: Interventional
• Enrollment (Estimated): 426
• 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: Adult; Older Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• Mothers aged ≥18 years with at least one child aged 3-6 years studying in kindergarten in Hong Kong
• Cantonese speaking
• Having smartphone with internet access
• Already having WhatsApp on the smartphone

Exclusion Criteria:

• Blindness or deafness
• The index child has known medical contraindications for seasonal influenza vaccination

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; Participants in the intervention group will receive chatbot-delivered online interventions tailored to their current stage of change regarding their index child's seasonal influenza vaccination.	Behavioral: Stage-of-change-tailored intervention; The Chatbot will deliver four intervention sessions tailored to participants' current stage of change regarding their index child's seasonal influenza vaccination uptake at Week 0, 2, 4, and 6. Participants will also have access to real-time Question-and-Answer (QA) function provided by the chatbot to address their questions related to seasonal influenza vaccination during the intervention period (week 0-6), and they are free to spend as much time as they want on such function.
Active Comparator: Control group; Participants in the control group will receive chatbot-delivered standard and non-stage-of-change-tailored interventions	Behavioral: Non-stage-of-change-tailored intervention; The Chatbot will automatically send participants a link to access a standard online video at week 0, 2, 4 and 6. Participants will also have access to real-time Question-and-Answer (QA) function provided by the chatbot to address their questions related to seasonal influenza vaccination during the intervention period (week 0-6), and they are free to spend as much time as they want on such function.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Index child's seasonal influenza vaccination uptake reported by his/her mother with validation	The research team will ask the participants whether their index children have taken up seasonal influenza vaccination at T2 (3 months after completion of the interventions) using a validated question through telephone interview. The research team will validate the outcome by requesting participants uploading an image of SIV receipt, while hiding personal identification, via the WhatsApp account used in this project.	3 months after completion of the interventions (T2)

Collaborators and Investigators

• Sponsor: Chinese University of Hong Kong

Study record dates

Study Major Dates

• Study Start (Estimated): August 1, 2026
• Primary Completion (Estimated): October 31, 2027
• Study Completion (Estimated): October 31, 2027

Study Registration Dates

• First Submitted: June 30, 2026
• First Submitted That Met QC Criteria: June 30, 2026
• First Posted (Actual): July 7, 2026

Study Record Updates

• Last Update Posted (Actual): July 7, 2026
• Last Update Submitted That Met QC Criteria: June 30, 2026
• Last Verified: June 1, 2026

More Information

Terms related to this study

• Keywords: Seasonal influenza vaccination uptake
• Other Study ID Numbers: HMRF24230092

Plan for Individual participant data (IPD)

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

Drug and device information, study documents

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