Study design and participants
We conducted two-arm, double-blind, randomised controlled trial in five cities in China (Beijing, Dezhou, Baotou, Yakeshi, and Linzi), with participants randomised to an intervention or control group between April 2021 and July 2021.We included daily or weekly smokers aged ≥18 who owned a mobile phone and used WeChat, and who agreed to participate by signing an informed consent form. We excluded individuals who had received any smoking cessation treatment within 30 days or had a diagnosis of any mental illnesses (either current or past).The Peking University registered the clinical trial (ChiCTR2100041942). We reported this study the following CONSORT reporting guidelines for randomised studies [