Introduction:
While the adult smoking rate in the Netherlands has decreased in the past years, the smoking prevalence of young adults (aged 18-24 years) remains high, with 28% in 2021. 85% of young adults wants to quit smoking. However, young adult smokers are generally not interested in using professional smoking cessation support (SCS). To provide suitable support to this group, we developed the mobile application “Quiddy”. The app matches young who want to quit smoking with each other, on the basis of personal characteristics and encourages them to provide support to each other during their quit process. The aim of this project was to study the adoption and implementation of the Quiddy app.

Material and Methods:
Registered users of the Quiddy app were invited to participate in a semi-structured qualitative interview through e-mail. Additional participants were recruited through social media. After participation, they received a 20 euro gift voucher. Additionally, professionals involved with the development of Quiddy were invited to participate in a semi-structured interview. The interview guide was informed by the RE-AIM framework.

Results:
Interviews were conducted with 9 young adults and 7 professionals. According to the respondents, next to regularly updated social media advertisements, they felt that Quiddy should be promoted through offline marketing to reach a more diverse group of young adults. Overall, the respondents were positive about Quiddy compared to other SCS. More specifically, they valued the high accessibility, supportive messages and the possibility to adapt the intervention to their needs. Nevertheless, most users were only partly familiar with the functionalities of Quiddy. The usage of different functionalities in the app, for example the option to chat with other users, varied strongly based on individual needs.

Conclusions:
Quiddy has the potential to increase smoking cessation among young adults. The study yields various important recommendations for health educators who want to develop interactive smoking cessation tools specifically for young adults. By incorporating recommendations regarding personalisation, motivation and interaction with other users, the engagement of young adults with Quiddy might further increase.