Opt-out policy and its improvements promote COVID-19 vaccinations.

"data sets and relevant scripts for data analysis are available online at https://osf io/4m9eg/ ."

"This research was supported by the 10.13039/501100001809National Natural Science Foundation of China (Grant No. 71771209), the Major Program of the 10.13039/501100012456National Social Science Foundation of China (Grant No. 19ZDA358), and the Project of the Mental Health and Social Governance Research Support Center, Academic Divisions of the Chinese Academy of Sciences (CASAD) (Grant No. E1CX052003). Xin Liu, Writing - Original Draft, Writing - Review & Editing, Data analyses. Ning Zhao, Writing - Original Draft, Data collection. Shu Li, Writing - Reviewing & Editing. Rui Zheng, Conceptualization, Methodology, Writing- Reviewing & Editing, Funding acquisition."