Characterizing Trends in Human Papillomavirus Vaccine Discourse on Reddit (2007-2015): An Observational Study

"Given the increasing use of social media as a source of health information, these results can inform the development of targeted online health communication strategies to promote HPV vaccination to young adult users of Reddit."

The rationale behind this study is that human papillomavirus (HPV) vaccination acceptance is a critical public health issue, as low completion rates of the vaccine series place adolescents and young adults at risk for HPV-associated infection and cancers. The multiple factors that influence vaccine acceptance have been examined on traditional mass media and social media. This study sought to assess whether discussions on Reddit - an online forum that allows users to post, share, and rank content - reflected the competing narratives (cancer risk vs. sexual promiscuity) in the broader media discourse and how these discussions influence decision making related to vaccination among both young women and young men.

To provide context for the study, the researchers examine HPV vaccination rates in the United States (US) and factors affecting uptake. For example, as HPV is sexually transmitted, some parents fear that vaccination will give license for adolescents to engage in early or risky sexual activity. The stigma associated with sexually transmitted infections (STIs) is exacerbated by the fact that the initial recommendation of HPV vaccination was for girls only, which has led to continued framing of HPV as a women's health issue, despite the fact that HPV affects both men and women. (A survey of the Reddit community revealed that 83.5% of participants identified themselves as aged between 18 and 34 years and that, of these, 80.4% identified themselves as male. Thus, this study hopes to provide insight into the male perspective on HPV vaccination, an understudied area.)

As reported here, both traditional and social media can influence public knowledge, attitudes, and behaviour around HPV vaccination, such as by (in the case of traditional media) mentioning sexual promiscuity rather than focusing on more pertinent details of vaccination (e.g., reducing HPV-associated cancers or discussing vaccination schedules and benefits). And social media may also have a strong impact on public perception of HPV vaccination risks. For example, Reddit permits users to post anonymously, allowing them to disclose personal behaviours more readily. And unlike microblogging social media platforms such as Twitter, Reddit does not limit message length, allowing users to express their opinions in depth. Reddit also has a strong community-based moderation culture.

The researchers gathered all public Reddit comments from January 2007 to September 2015. From the total set, they identified a subset of HPV-related messages by filtering all comments containing the text "hpv" or "human papillomavirus". From the set of hpv-related messages, they further identified a subset of vaccine-related messages by filtering messages for the string "vaccin". (Mitigating concerns about behaviour by malicious actors, such as bots, they found that no two messages in the dataset were exactly the same, a common indicator of bot behaviour.) They then measured the similarity between each comment and lists of keywords associated with sexual behaviour and cancer risk using Latent Semantic Analysis (LSA). Next, they used Latent Dirichlet Allocation (LDA) to characterise remaining topics within the Reddit data.

Of the 22,729 messages analysed, LSA findings show that HPV vaccine discussions were significantly more related to cancer compared with sexual behaviour from 2008 to 2015 (P<.001). Namely, of the total set of HPV-vaccine-related Reddit messages, 16.1% were focused on cancer risk topics, and 14.5% were focused on HPV related to sexual activity. However, even when combined, these two topics represented less than one-third of the total HPV-vaccine-related messages on Reddit. This is in contrast with the mainstream media's focus on sexual behaviour linked to HPV vaccine.

LDA analyses demonstrated that although topics related to cancer risk and sexual activity were both frequently discussed, the majority of online discussions featured other topics. The most frequently discussed topic was politics associated with the vaccine (17.2%). Other topics included HPV disease and/or immunity (13.5%), the HPV vaccine schedule (11.5%), HPV vaccine side effects (9.7%), hyperlinks to outside sources (9.1%), and the risks and benefit of HPV vaccination (8.5%).

The researchers identified trends, such as the fact that HPV-related messages spiked in 2008, perhaps associated with media attention surrounding state consideration for school vaccination mandates for middle-school age girls. The following year also saw spikes in messages representing vaccine debate, perhaps associated with the introduction of a second HPV vaccine, Cervarix, in 2009. There were continued increases in discussion through 2011 and 2012, most likely due to the US Centers for Disease Control and Prevention (CDC) HPV vaccine recommendations for boys in fall 2011 coinciding with the 2012 presidential campaign, which incited debates around vaccination. On the other hand, increases in cancer discussions during 2013 and sexual activity in 2014 do not coincide with major policy changes or announcements and thus warrant additional research.

The researchers did not find a significant difference between genders in discussions of cancer and sexual activity (P>.05). Thus, analyses did not support the idea of HPV as primarily a woman's health issue on Reddit. The LDA findings also challenge the notion that HPV is perceived as an issue affecting women exclusively, with sizable discussion on Reddit on HPV prevention for men related to circumcision. The circumcision debate indicates broader concerns of men concerned with STI and cancer prevention related to HPV. These results further emphasise the difference between discussions on Reddit and media representations on the HPV vaccine.

In addition to the diversity in topics, it appears users were turning to Reddit for a variety of reasons: Some were posing questions and were looking for answers; others seemed to want to debate; some wanted to discuss topical issues in the news; and still others seemed to want to make jokes. Messages ranged from one-word responses to posts a few thousand words long. Some were based on personal experiences and anecdotes, and others were based on facts and statistics, often linking to cited research. The researchers suggest that, by highlighting the topics most salient to Reddit users, public health communication efforts can be targeted to suit the needs of this online community. In addition, the range and extent of messages from users seeking information highlights a gap in accessible credible information online.

More specifically, health care provider (HCP) recommendation has been found to be critical to vaccine uptake, yet physicians are more likely to recommend other vaccines (e.g., tetanus and diphtheria) compared with HPV vaccine. Lacking HCP recommendations or accurate knowledge, users may turn to online forums such as Reddit seeking advice, which may be filled with inaccurate information. In addition, without provider and public health engagement in these forums, misconceptions surrounding HPV vaccination may proliferate, fueling vaccine hesitancy.

As young adults increasingly use Web-based resources to seek health information, the researchers recommend that public health officials develop health communication strategies that engage users, such as answering questions through Ask Me Anything events on Reddit or enlisting experts or well-known public figures to promote vaccination. Providers can share accurate HPV information and engage with patients regarding their questions and concerns regarding HPV vaccination, using this platform to address concerns of Web-based communities to the extent they are representative of the broader public, instead of concerns of the news cycle. "Although the increased effort of targeted engagement with users online will require more resources (ie, dedicated time) from public health agencies, the opportunities to reach and impact HPV vaccination greatly outweigh the challenges."