Characterisation of the online public debate od MMR vaccine against measles, mumps and rubella on the Polish Internet.

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.