List of keywords used for filtering vaccine-related content.

Table reports keywords divided by vaccine type: General, Covid-19 vaccines, Mandatory and Recommended vaccines (Law 119/2017), Other authorized and marketed vaccines. The special character * stands for zero or more non-whitespace characters. The list does not include the term ‘immunizzazione’ (immunization) and its variations, since anti-vaccination contents almost never talks about immunization [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0316258#pone.0316258.ref065" target="_blank">65</a>,<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0316258#pone.0316258.ref066" target="_blank">66</a>]. Obviously, this is expected since anti-vaccination groups tend not to believe that vaccines confer immunity. Possible uses of the searched keywords in contexts other than the discussion on vaccines are, of course, quite rare. However, in the manual annotation process concerning stance and topic, we observed that the only critical cases involved content containing references to ‘latte vaccino’ (vaccine milk). Such content has been removed from the dataset. (DOCX)