LAUSR

INTRODUCTION MMR vaccine is a controversial topic of public debate. The controversies include such issues as autism, adjuvants or ethical questions related to the culturing of the rubella virus on human cell lines. OBJECTIVE The objective was to characterise the public debate on MMR vaccination on the Polish Internet between January 2018 and June 2020. MATERIAL AND METHODS Quantitative and qualitative analysis of Polish-language online content between 1 January 2018 and 30 June 2020 related to MMR vaccination. The quantitative analysis comprised all available mentions of MMR vaccination in postings (n=14,632), while qualitative analysis relied on a systematic sample of 819 mentions. RESULTS Quantitative study: 79.6% of MMR vaccine-related postings were published on Facebook, 6.9% on Twitter, and the remaining 14.6% appeared on other websites. There were two surges in posting count in November 2018 and March 2019. Qualitative study: 48% of postings expressed anti-vaccination sentiment, 33% were pro-vaccination and 19% were neutral. CONCLUSIONS The social media play a significant role in the dissemination of untrue medical claims regarding MMR vaccination. A substantial part of the discussion about MMR vaccination in Poland takes place on Facebook. Despite the general availability of research results stating the absence of a link between autism and vaccination, this is an ongoing most frequent topics in the MMR debate. At the same time, more postings on that topic expressed pro-vaccination rather than anti-vaccination sentiment.