From 2013 to 2015, Denmark saw an exponential rise in adverse events reported for Human Papilloma Virus (HPV) vaccines and later a dramatic drop in HPV vaccine compliance. It is generally believed that Danish media and social media played an important role in these events by spurring vaccine skepticism, vaccine anxiety and moral panic through negative coverage and circulation of misinformation. Yet, how do we know it? In this paper, we discuss the Big Data and quantitative methods available for analysing the role of social media in the Danish HPV case. We make use of Ian Hacking’s framework for understanding the possibility of transient mental illness and argue that ‘social media’ represents many different phenomena acting in many different ways. We suggest a combination of digital cartography, narrative-break analysis and ethnography as key ways of exploring the different digital vectors at play – and gaining an eclectic understanding of what happened in Denmark in 2013-2015.