Background Over the past decade, there has been an increasing secular trend in the number of studies on social media and health. Objective The purpose of this cross-sectional study was to examine the content and characteristics of TikTok videos that are related to an important aspect of community mitigation—the use of masks as a method for interrupting the transmission of SARS-CoV-2. Methods In total, 100 trending videos with the hashtag #WearAMask (ie, a campaign on TikTok), along with 32 videos that were posted by the World Health Organization (WHO) and involved masks in any way (ie, all related WHO videos at the time of this study), were included in our sample. We collected the metadata of each post, and created content categories based on fact sheets that were provided by the WHO and the US Centers for Disease Control and Prevention. We used these fact sheets to code the characteristics of mask use. Results Videos that were posted on TikTok and had the hashtag #WearAMask garnered almost 500 million views, and videos that were posted by the WHO garnered almost 57 million views. Although the ratio of the number of trending #WearAMask videos to the number of WHO videos was around 3:1, the #WearAMask videos received almost 10 times as many cumulative views as the WHO videos. In total, 68% (68/100) of the trending #WearAMask videos involved humor and garnered over 355 million cumulative views. However, only 9% (3/32) of the WHO videos involved humor. Furthermore, 27% (27/100) of the trending #WearAMask videos involved dance and garnered over 130 million cumulative views, whereas none of the WHO videos involved dance. Conclusions This study is one of the first to describe how TikTok is being used to mitigate the community spread of COVID-19 by promoting mask use. Due to the platform’s incredible reach, TikTok has great potential in conveying important public health messages to various segments of the population.

BACKGROUND Over the past decade, there has been an increasing secular trend in studies of social media and health. OBJECTIVE The purpose of this cross-sectional study was to examine the content and characteristics of TikTok videos related to an important aspect of community mitigation, namely use of masks as a way to interrupt transmission of SARS-CoV-2. METHODS One-hundred trending video with the hashtag #WearAMask, a campaign on TikTok, along with 32 videos posted by the World Health Organization (WHO) that included masks in any way (to date) were included in the sample. Metadata on each post and content categories created using fact sheets from WHO and the US Centers for Disease Control and Prevention (CDC) inform characteristics that were coded. RESULTS Videos posted using the hashtag #WearAMask garnered almost a half billion views, (n = 494,824,395) and videos posted by the WHO garnered over 57 million views. While the ratio of trending #WearAMask to WHO videos was ~3:1, the #WearAMask videos received almost 10 times as many cumulative views. A total of 68% of the trending #WearAMask videos used humor (garnering over 355 million cumulative views), but only three of the WHO videos used humor, and while 27% of the trending #WearAMask videos used dance (garnering over 130 million cumulative views), none of the WHO videos used dance. CONCLUSIONS This study is one of the first to describe how TikTok is being used for community mitigation of COVID-19 by promoting mask use. Because of its incredible reach, there is great potential to convey important public health messages to various segments of the population.