HPV vaccine coverage in Australia and associations with HPV vaccine information exposure among Australian Twitter users

Figures & data

Table 1. Models of HPV vaccination coverage for 31 Twitter-derived topic exposure and 5 socioeconomic factors in 25 combined Primary Health Network regions in Australia.

Model	Factors used	Pearson’s R (95% CI)	r^2
Adolescent female coverage
Employment	2/2	0.33 [−0.09 to 0.65]	0.07
Employment and education	3/4	0.39 [−0.02 to 0.68]	0.11
Twitter-derived topic exposure	7/31	0.75 [0.49 to 0.88]	0.54
All factors	6/35	0.63 [0.30 to 0.82]	0.36
Adolescent male coverage
Employment	2/2	0.34 [−0.06 to 0.65]	0.08
Employment and education	3/4	0.36 [−0.04 to 0.66]	0.09
Twitter-derived topic exposure	9/31	0.76 [0.51 to 0.89]	0.55
All factors	14/37	0.90 [0.78 to 0.95]	0.80

Table 2. Topics group descriptions and total potential exposure counts.

Group	Localised exposures	Description
I	2,999,860	Conspiracy theories, misrepresentations of safety research published in journals without rigorous peer review, and one media controversy (a television show hosted by Kate Couric in the United States).
II	2,931,294	Mostly tweets that were vaccine-critical, links to blog posts and YouTube videos describing individual harms and adverse events, but also included mixed positive and negative opinions about a media controversy (the reversal of an example of false balance in the Toronto Star newspaper).
III	3,106,994	Mixed positive and negative topics including discussions about individual experts in the area, parental decision making, research on the effects of different numbers of doses, and experiential tweets.
IV	3,462,772	All positive topics that included information for clinicians, discussions of the use of HPV vaccines in boys, and new research showing that HPV vaccination was not linked to riskier sex.
V	4,821,648	All positive topics describing coverage, new research about rates of HPV in the United States, and stories about vaccination coverage and successes from outside of the United States (including Australia).
VI	4,095,442	Mixed positive and negative topics, including debates about research and the link between HPV and cervical cancer, and discussions about policy and guidelines (including HPV vaccines for boys and gay men), and meta-discussions about misinformation and anti-vaccine rhetoric.

Figure 1. The hierarchical structure of topics determined from the set of intrusion tests performed over the 30 topics (Appendix 1), and included in one of 6 groups (Table 2). Exposure counts represent the total number of unique Australian Twitter users (of those localised to one of the 25 geographical regions) who may have been exposed to tweets from that topic. Orange groups tend to include mostly negative topics and cyan groups tend to include mostly positive topics. Differences in colour were used to denote groups across figures.

Figure 2. Potential exposures among Australian Twitter users per week in the period 6 September 2013 to 1 September 2017. Peaks correspond to (a) Australian research showing cervical cancer risk was reduced; (b) Canadian and Australian research showing cervical cancer risk was reduced; (c) Reduction in cervical cancer risk in the United States; (d) discussions of coverage rates in Australia and reduction in risk in New Zealand; (e) research showing that one dose may be enough; (f) debates about the representation of HPV vaccines on a television show hosted by Katie Couric; (g) responses to the reversal of a false balance story written in the Toronto Star newspaper; and (h) videos and stories of adverse events and harm.

Figure 3. Examples of topic exposure within individual cities in Australia by topic group (I-VI, inset), where bars represent the city-level difference in proportional exposure to each of the 6 topic groups relative to proportional exposure for all Australian Twitter users. The map illustrates differences in HPV vaccine coverage (population-weighted 3 dose completion aggregated for female and male adolescents) across the 31 Primary Health Networks (PHNs).