This study investigates linguistic devices and discursive strategies employed by online social movement organizations (SMOs) in attempts to deinstitutionalize long-standing, institutionalized behaviors. The research draws from an in-depth analysis of public discourse within anti-vaccine online communities in Italy and contributes to the social movement literature on framing and the theory of discursive institutionalization. It employs semi-automated text-analysis methods and interpretive analysis of textual data from seven anti-vaccine social media communities, before and subsequent to the 2017 regulatory intervention of the Italian government to increase vaccination rates. This intervention followed a phase of intense debate centered on the decrease in vaccination coverage and the spread of anti-vaccine ideas in social media as well as in the broader public discourse. The study analyzes the discursive strategies and linguistic devices of community leaders (moderators) and followers (members), and investigates shifts in micro-level online anti-vaccine discursive strategies that developed after the government regulation. The findings suggest that anti-vaccine online SMOs employ specific sets of linguistic devices, namely rhetorical fallacies, that support well-defined discursive strategies such as those aiming to delegitimize actors that endorse vaccines. Furthermore, the evidence shows that these linguistic devices and discursive strategies, after the government regulation, shift from an evidence-based stance towards values and emotions-based argumentations.

本研究调查了在线社会运动组织 (SMO) 采用的语言手段和话语策略，试图将长期存在的制度化行为去制度化。该研究对意大利反疫苗在线社区中的公共话语进行了深入分析，并为有关框架和话语制度化理论的社会运动文献做出了贡献。在意大利政府于 2017 年进行监管干预以提高疫苗接种率之前和之后，它采用了半自动文本分析方法和来自七个反疫苗社交媒体社区的文本数据的解释性分析。这种干预是在围绕疫苗接种覆盖率下降和反疫苗思想在社交媒体以及更广泛的公共话语中传播的激烈辩论之后进行的。该研究分析了社区领导者（版主）和追随者（成员）的话语策略和语言手段，并调查了政府监管后形成的微观层面的在线反疫苗话语策略的转变。研究结果表明，反疫苗在线 SMO 使用特定的语言工具集，即修辞谬误，支持明确定义的话语策略，例如旨在使支持疫苗的行为者非法化的策略。此外，有证据表明，这些语言手段和话语策略，在政府监管之后，