List of infectious diseases notifiable in mainland China according to the Law of the People’s Republic of China on the Prevention and Treatment of Infectious Diseases (as of 2012), and the corresponding keywords used to search Weibo posts.

*Class A and B diseases require immediate notification to health authorities of a higher administrative level; Class C diseases require periodical notification. Class A refers to diseases highlighted in the International Health Regulations [28] that may constitute a public health emergency of international concern, of which cholera and plague (listed in the law) are (or were) endemic in parts of China. The law specified that outbreaks of class A diseases require prompt infection control measures including immediate isolation of patients and quarantine (medical observation) of their contacts. Collection, transportation and testing specimens of Class A pathogens require approval from the provincial authorities or the central government [27].† Influenza A(H1N1) was classified as a Class B infectious disease and was added to the list as a separate entity during the 2009 pandemic [29]. On October 28, 2013, it was announced by the Chinese government that starting from January 1, 2014, influenza A(H1N1) would cease to be listed separately and would be grouped with other influenza strains as an aggregated number listed in Class C [30].List of infectious diseases notifiable in mainland China according to the Law of the People’s Republic of China on the Prevention and Treatment of Infectious Diseases (as of 2012), and the corresponding keywords used to search Weibo posts.