Title: Pay-it-forward to improve influenza vaccine uptake and public engagement among children and older adults in China Dan Wu 1,2,3,*,# , Chenqi Jin 2,4,# , Khaoula Bessame 1 , Fanny Fong-Yi Tang 1,5 , Jason J. Ong 1,6,7 , Zaisheng Wang 2,8 , Yewei Xie 2,9 , Mark Jit 10 , Heidi J. Larson 10 , Tracey Chantler 11 , Leesa Lin 10,12 , Wenfeng Gong 13 , Fan Yang 14 , Fengshi Jing 2,15 , Shufang Wei 2 , Weibin Cheng 15 , Yi Zhou 16,17 , Nina Ren 15 , Shuhao Qiu 18 , Jianmin Bao 19 , Liufen Wen 20 , Qinlu Yang 21 , Junzhang Tian 15 , Weiming Tang 2,4,22,*,§ , Joseph D. Tucker 1,2,22,§ 1. Department of Clinical Research, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK. 2. University of North Carolina at Chapel Hill Project-China, Guangzhou, China 3. West China School of Public Health, Sichuan University, Chengdu, China 4. Dermatology Hospital of South Medical University, Guangzhou, China 5. Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China 6. Central Clinical School, Faculty of Medicine, Monash University, Melbourne, Australia 7. Melbourne Sexual Health Centre, Alfred Health, Melbourne, Australia 8. School of Health and Related Research, The University of Sheffield, Sheffield, UK. 9. Duke Global Health Institute Duke University, North Carolina, U.S. 10. Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, London, UK. 11. Faculty of Public Health and Policy, London School of Hygiene and Tropical Medicine, London, UK. 12. Laboratory of Data Discovery for Health (D24H), Hong Kong Science Park, Hong Kong, China 13. Beijing Representative Office, Bill & Melinda Gates Foundation, Beijing, China 14. Institute of Population Research, Peking University, Beijing, China 15. Guangdong Secondary Provincial General Hospital, Guangzhou, China 16. Zhuhai Center for Disease Control and Prevention, Zhuhai, China 17. Faculty of Medicine, Macau University of Science and Technology, Macau SAR, China 18. Vaccination Clinic, Yangshan Health Centre, Qingyuan, China. 19. Fenghuang Community Health Service Centre, Zengcheng, China. 20. Xinghua Community Health Service Centre, Guangzhou, China. . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) The copyright holder for this preprint this version posted November 1, 2021. ; https://doi.org/10.1101/2021.10.30.21265713 doi: medRxiv preprint NOTE: This preprint reports new research that has not been certified by peer review and should not be used to guide clinical practice.