ABSTRACT: BACKGROUND:The battle against COVID-19 remains ongoing, and social media has played an important role during the crisis for both communication and health promotion, particularly for health care organizations. Taiwan's success during the COVID-19 outbreak is well known and the use of social media is one of the key contributing factors to that success. OBJECTIVE:This nationwide observational study in Taiwan aimed to explore the use of Facebook by academic medical centers during the COVID-19 pandemic. METHODS:We conducted a nationwide observational study of all Facebook fan page posts culled from the official accounts of all medical centers in Taiwan from December 2019 to April 2020. All Facebook posts were categorized into either COVID-19-related posts or non-COVID-19-related posts. COVID-19-related posts were split into 4 categories: policy of Taiwan's Center for Disease Control (TCDC), gratitude notes, news and regulations from hospitals, and education. Data from each post was also recorded as follows: date of post, headline, number of "likes," number of messages left, number of shares, video or non-video post, and date of search. RESULTS:The Facebook fan pages of 13 academic medical centers, with a total of 1816 posts, were analyzed. From January 2020, the percentage of COVID-19 posts increased rapidly, from 21% (January 2020) to 56.3% (April 2020). The trends of cumulative COVID-19 posts and reported confirmed cases were significantly related (Pearson correlation coefficient=0.93, P<.001). Pages from private hospitals had more COVID-19 posts (362 versus 289), as well as more video posts (72 posts, 19.9% versus 36 posts, 12.5%, P=.011), when compared to public hospitals. However, Facebook pages from public hospitals had significantly more "likes," comments, and shares per post (314, 5, 14, respectively, P<.001). Additionally, medical centers from different regions displayed different strategies for using video posts on Facebook. CONCLUSIONS:Social media has been a useful tool for communication during the COVID-19 pandemic. This nationwide observational study has helped demonstrate the value of Facebook for academic medical centers in Taiwan, along with its engagement efficacy. We believe that the experience of Taiwan and the knowledge it can share will be helpful to health care organizations worldwide during our global battle against COVID-19.