1. Introduction Recent measles outbreak in British Columbia and Alberta demonstrates a dire need for policy-makers to become more proactive in engaging citizens in decision-making. Anti-vaccination movements are not a new problem nor is it an objective phenomenon. Instead, they are the interpretations from particular perspectives (Mannheim, 1936). Medicine in the 21 st century is a post- modernist challenge to Evidence-Based Medicine (EBM) because it signifies that decision-making processes are subject to form opinions based on both evidence and values (Gray, 1999). This research aims to identify the social constructs on target groups in the online community, explore the gaps of Web engagement by pro-vaccination and Anti- vaccination groups, and explore future steps for entrepreneurship in health-policy countering Anti-vaccination movements. Materials and methods Using the theory of social construction of target groups (Schneider and Ingram, 1993), this study identifies the quadrants of social hierarchy of key supporters and opponents in the online Anti-vaccination community. This research navigated contents online to calculate the use of web 1.0 (unilateral informational posts) and web 2.0 (real-time interactive feeds) for the above groups using ww.soicalmention.com and other crowd- sourcing websites. Applying multiple streams framework, this study examined the means through which agencies can engage in policy entrepreneurship to create opportunities to merge three streams to counter Anti- vaccination movements (Kingdon, 2002). Acknowledgments My sincere thanks to supervisor Dr. Julia Abelson for providing invaluable guidance and funding throughout the research. I thank Anna Kata for a fruitful discussion on her research on Anti-vaccination claims. Special thanks to my colleagues at CHEPA and the philosophy department at McMaster for proof-reading, and anonymous social media savvy bloggers who have exchanged dialogues with me. Results Preliminary research shows that government agencies belong to the advantaged quadrant in the social construction in the online community. Non- profit organizations are perceived as either contenders or advantaged advocates for the dependents (i.e. target subject for vaccines and their decision makers). Agencies supporting Anti- vaccination movements are perceived as deviants and advocates for the dependents. As of March, 2014, results for measuring agency engagement shows mainly neutral (see Chart 1), although there is a lack of engagement for pro-vaccination agencies in Web 2.0 activities (see Chart 2). Chart 1. Sentiments of Anti-vaccine claims on Web 1.0 and Web 2.0 (March, 2014) Based on keyword on Google search engine, fourteen methods of engagement emerged. In Web1.0, methods include setting up websites allowing contact by email, websites with downloadable brochures, informational websites with FAQs, blogs with professional information, websites containing vaccine information with a recognizable spokesperson, applications on portable devices with immunization alerts. These forms of engagement are unilateral and provide no opportunity for direct feedback or bilateral engagement. As chart 2 demonstrates, Anti- vaccination agencies occupy the internet by engaging in Web 1.0 and Web 2.0 services. Chart 2. Engagement on Web 1.0 and Web 2.0 Conclusions In the advent of media 2.0, the role of government agencies’ involvement or its lack thereof on the internet needs re-evaluation. This research analyzes the multitude of social media engagement channels health policy-makers could use to counter saliency on health misinformation in online communities in a Canadian context. Melodie Yun-Ju Song Health Policy PhD student, Department of Clinical Epidemiology and Biostatistics, Center for Health Economics and Policy Analysis, McMaster University Literature cited Mannheim, K. (2013). Ideology and utopia. Routledge. Gray, J. A. (1999). Postmodern medicine. The Lancet, 354(9189), 1550- 1553. Kata, A. (2010). A postmodern Pandora's box: Anti-vaccination misinformation on the Internet. Vaccine, 28(7), 1709-1716. Schneider, A., & Ingram, H. (1993). Social construction of target populations: Implications for politics and policy. American political science review, 87(02), 334-347. Kingdon, J. (2002). The reality of public policy making. Ethical dimensions of health policy, 97-116. Further information Inquiries on research results welcomed, you may reach me at songy42@mcmaster.ca, or follow me on Twitter @MelodieYJSongsongy42@mcmaster.ca Policy Entrepreneurship – Is There Room for Public Health Professionals to Speak Up Against Anti-vaccination Movements in Cyberspace? On the other hand, Web 2.0 engagements are prominent in the form of active interactions on Twitter, Facebook, and blogs where authors respond to the questions of the community, websites with direct number for informational inquiry, discussion forums, webpages allowing comments and feedback, applications on mobile devices with personalized immunization plans and live newsfeed, and presence of recognizable spokespersons engaging in social media. Web 2.0 creates real-time interactive dialogues with readers, and, often, throughout the process, allows for constant feedback and re-iteration of information/misinformation. In multiple streams framework, policy entrepreneurship from government agencies in the political stream are less prominent than non-profit agencies. Policy entrepreneurship from agencies supporting Anti-vaccination movements have successfully created issues in the problems stream, presented solutions in the policies stream, and gained momentum in the politics stream. Discussion Social construction of target groups indicate that parent-initiated non-profit groups on the internet poses great threats for pro-vaccination agencies. It is common in Anti-vaccination websites to use tactics such as skewing the science, shifting hypothesis, censorship, attacking the opposition to counter pro- vaccination information (Kata, 2012). These tactics promotes Anti-vaccination salience in social media, more specifically, under the name of non-profit organizations found by parents; these organizations easily appeal to the audience by updating readers on the newest campaigns, evidence in its favor and referrals to trusted sources. Policy-makers have failed to thwart online Anti- vaccination movements partly due to (1) a failed policy-reaction towards a moving ‘arena’ of dialogue in cyberspace, (2) a paradigm shift of postmodernism of interpretation on vaccines that Evidence-Based Medicine alone cannot solve, (3) lack of coherent action plans for policy windows to open to counter Anti-vaccination movements.