Virtual Zika Transmission after the first US Case: Who said What and How It Spread on Twitter

Background: This paper goes beyond detecting specific themes within Zika-related chatter on Twitter, to identify the key actors who influence the diffusive process through which some themes are more amplified than others are. Methods: We collected all Zika-related tweets during the three months immediately after the first U.S. case of Zika. Following categorization into twelve themes, a cross-section of tweets were grouped into weekly datasets to capture 12 amplifier/user groups and analysed by four amplification modes: mentions, retweets, talkers, and twitter-wide amplifiers. Results: We analysed 3,057,130 tweets in the US and categorized 4,997 users. The most talked about theme was Zika transmission (~58%). News media, public health institutions and grassroots users were the most visible and frequent sources and disseminators of Zika-related Twitter content. Grassroots users were the primary source and disseminators of conspiracy theories. Discussion & Conclusions: Social media analytics enable public health institutions to quickly learn what information is being disseminated, and by whom, regarding infectious diseases. Such information can help public health institutions identify and engage with news media and other active information providers. It also provides insights into media and public concerns, accuracy of information on Twitter, and information gaps that may exist. The study identifies implications for pandemic preparedness and response in the digital era and presents the agenda for future research and practice