Promoting Smoking Cessation in the Community Via "Quit to Win" Contest 2026: Engagement-Focused GenAI-based Chatbot for Real-Time Smoking Cessation Support

The goal of this trial is to learn if chatbot-based instant messaging works to help smoking cessation in general adult smokers. It will also learn about the experience, attitude, and perception of using an LLM-based chatbot. The main questions it aims to answer are: 1. Will an engagement-focused LLM-based chatbot smoking cessation intervention have a non-inferior validated abstinence rate than the control group? 2. Will an LLM-based chatbot smoking cessation intervention have a non-inferior self-reported abstinence rate, smoking reduction rate, and smoking cessation services use rate than the control group? Researchers will compare an LLM-based chatbot smoking-cessation intervention to a human-led instant messaging support group (brief advice based on AWARD and personalised active referral) to determine whether chatbot-based instant messaging support promotes smoking cessation. Participants in the intervention group will receive: 1. AWARD advice 2. Personalised active referral 3. 12 weeks of chatbot-based instant messaging support (via WhatsApp)

Inclusion Criteria: 1. Hong Kong residents aged 18 years or above 2. Smoke at least one cigarette (including heated tobacco products) per day or use an e-cigarette daily in the preceding 3 months 3. Able to communicate in Cantonese (including reading and writing Chinese) 4. Saliva cotinine level ≥30 ng/mL 5. Intention to quit or reduce smoking 6. Have WhatsApp installed 7. Able to use WhatsApp for communication Exclusion Criteria: 1. Smokers who have communication barriers (either physical or cognitive) 2. Smokers who are currently participating in other smoking cessation programs or services