The negative perceptions of vaccines that are held by a small proportion of parents—specifically, a view that the potential risks of vaccination far outweigh any associated benefits—can contribute to outbreaks of vaccine-preventable diseases. For example, over the last 12 months there have been numerous measles outbreaks across Europe, resulting in thousands of infections and 31 deaths, despite the widespread availability of highly effective vaccines.
Anti-vaccine feelings among the general public have largely focused on concerns surrounding vaccine safety. The most prevalent myth regarding vaccines has been claims of a link between the development of autism spectrum disorder (ASD) in children and vaccination. This association, which has been extensively researched over the last couple of decades, has been found to be unsubstantiated. But despite scientific consensus that vaccines are safe and do not cause ASD, these beliefs continue to be commonly mentioned online and in the media.
Even though the perceived motivation for withholding immunisations it to keep children safe, those who do not receive vaccines are at a significantly higher risk of acquiring vaccine-preventable diseases. Low vaccination rates can also potentially undermine the health of the wider community by compromising herd immunity, allowing for disease outbreaks to occur.
Given the fact that anti-vaccine beliefs continue to be perpetuated on the internet, understanding how these views are spread among different groups of people online could help public health advocates to combat these harmful views. It is possible to monitor these views through an analysis of social media activity, a method for evaluating pubic consensus referred to as social listening.
A recent study by University of Alabama assistant professor Theodore Tomeny and colleagues examined who is most likely to harbor negative attitudes about vaccines by monitoring online activity, so that these misconceptions could be addressed in a more targeted fashion. During the study, 549,972 vaccine-related tweets made from 2009–2015 across the US were analysed by Tomeny and colleagues. Anti-vaccine tweets were identified by keywords commonly associated with negative opinions of vaccines, such as “ineffective,” “unsafe,” and “autism”. Interestingly, geographic areas with a disproportionate level of anti-vaccine beliefs were associated with larger, more affluent populations that had higher concentrations of new mothers. These regions also had higher levels of education, meaning that individuals who were likely to be more informed of the benefits of vaccinations were more outspoken about rumors and speculations regarding vaccine safety. The study’s findings were in line with those from numerous social studies surrounding anti-vaccine beliefs.
Social listening studies such as this can be completed cheaply and in real time, unlike traditional surveys. The speed at which the public reaction to current health-related events could be evaluated with this approach was highlighted by sudden peaks in anti-vaccine tweets during vaccine-related news; such as in the case of the “CDC Whistleblower” story.
Knowledge of which individuals are most likely to refuse or delay vaccinations for their children is vital in the struggle to increase vaccination rates and successfully protect communities from infectious diseases. Social listening, as demonstrated by this study, can identify those most likely to refuse vaccinations as well as monitor real-time shifts in public opinion. Therefore, it has the potential to be a powerful tool in campaigns aiming to tackle misconceptions about vaccine safety and improve vaccination rates.