Chinese online community's discussion related to SARS, January - June 2013. The daily numbers of posts that contain a keyword per million posts in the sample of about 50,000 users that have ≥10,000 followers, January 1 to June 30, 2013 are shown here. 非典, (Feidian, short for fei-dianxing-feiyan, translated, “atypical pneumonia”) is the layman’s term for SARS in China. Notes: (1) On January 31, 2013, in an interview with the media, Prof. ZHONG Nan-Shan, a famous Chinese medical expert with a high reputation from his experience fighting against SARS in 2003, mentioned that air pollution in China is more dreadful than “Feidian” because no one can escape from it. His quote from the interview was re-posted widely by Weibo users on that day. (2) Beginning on March 31, 2013, Weibo posts with keywords “Feidian” or SARS skyrocketed, and reached a peak on April 3, 2013. Likewise, Weibo posts with keywords “沙士” (SARS) or “冠状病毒” increased, and reached a peak on April 5, 2013.