**2. Methods**

### *2.1. Participants and Procedures*

The current study was based on dataset of the Survey of Health Behaviors During the COVID-19 Pandemic in Taiwan, which was initially reported elsewhere [22]. The expert meeting was held to develop questionnaires, which were used in this study. In brief, Facebook users aged ≥20 years and living in Taiwan were recruited into this study between 10 April and 23 April 2020. A Facebook advertisement was posted, which included a headline, main text, pop-up banner and weblink to the research questionnaire website. The recruiting advertisement was designed to appear in the "News Feed" of Facebook, which is a streaming list of updates from the user's connections (e.g., friends) and advertisers. A previous study indicated that News Feed advertisements are more effective in terms of recruitment metrics for research studies [23]. In order to increase its visibility, we also posted the online advertisement to Line and Facebook groups.

This study was approved by the Institutional Review Board of Kaohsiung Medical University Hospital (approval no. KMUHIRB-EXEMPT(I)20200011). Although the participants were not given any incentive for their participation, at the end of the questionnaire we provided them with weblinks to the online COVID-19 Information Centers of the Taiwanese CDC, Kaohsiung Medical University Hospital, and the Medical College of National Cheng Kung University so they could search for useful information.
