“Vaccines for pregnant women…?! Absurd” – Mapping maternal vaccination discourse and stance on social media over six months

Objectives. To understand how Twitter bots and trolls (“bots”) promote online health content. Methods. We compared bots’ to average users’ rates of vaccine-relevant messages, which we collected online from July 2014 through September 2017. We estimated the likelihood that users were bots, comparing proportions of polarized and antivaccine tweets across user types. We conducted a content analysis of a Twitter hashtag associated with Russian troll activity. Results. Compared with average users, Russian trolls (χ 2 (1) = 102.0; P  < .001), sophisticated bots (χ 2 (1) = 28.6; P  < .001), and “content polluters” (χ 2 (1) = 7.0; P  < .001) tweeted about vaccination at higher rates. Whereas content polluters posted more antivaccine content (χ 2 (1) = 11.18; P  < .001), Russian trolls amplified both sides. Unidentifiable accounts were more polarized (χ 2 (1) = 12.1; P  < .001) and antivaccine (χ 2 (1) = 35.9; P  < .001). Analysis of the Russian troll hashtag showed that its messages were more political and divisive. Conclusions. Whereas bots that spread malware and unsolicited content disseminated antivaccine messages, Russian trolls promoted discord. Accounts masquerading as legitimate users create false equivalency, eroding public consensus on vaccination. Public Health Implications. Directly confronting vaccine skeptics enables bots to legitimize the vaccine debate. More research is needed to determine how best to combat bot-driven content.

Maternal vaccination has been evaluated and found to be extremely effective at preventing illness in pregnant women and new-borns; however, uptake of such programmes has been low in some areas. To analyse factors contributing to uptake of vaccines globally, a systematic review on vaccine hesitancy was carried out by The Vaccine Confidence Project in 2012. In order to further analyse factors contributing to uptake of maternal immunisation, a further search within the broader systematic review was conducted using the terms 'Pregnan*' or 'Matern*'. Forty-two articles were identified. Pregnancy-related articles were further screened to identify those focused on concerns, trust and access issues regarding maternal vaccination reported by pregnant women and healthcare workers. Thirty-five relevant articles were included which were then searched using the snowballing technique to identify additional relevant references cited in these articles. A search alert was also conducted from February to April 2015 in PubMed to ensure that no new relevant articles were missed. A total of 155 relevant articles were included. Most of the literature which was identified on hesitancy surrounding vaccination during pregnancy reports on determinants of influenza vaccine uptake in North America. Research conducted in low-income countries focused primarily on tetanus vaccine acceptance. The main barriers cited were related to vaccine safety, belief that vaccine not needed or effective, not recommended by healthcare worker, low knowledge about vaacines, access issues, cost, conflicting advice. From the point of view of healthcare workers, barriers included inadequate training, inadequate reimbursement and increased workload. Twenty-seven out of 46 (59%) articles mentioning ethnicity reported lower rates of coverage among ethnic minorities. Barriers to vaccination in pregnancy are complex and vary depending on context and population. There are wide gaps in knowledge regarding the attitudes of healthcare workers and how ethnicity and gender dynamics influence a pregnant woman's decision to vaccinate.

ABSTRACT Europe is increasingly described as the region in the world with the least confidence in vaccination, and particularly in the safety of vaccines. The aim of this systematic literature review was to gather and summarise all peer-reviewed and grey literature published about determinants of Human Papillomavirus (HPV) vaccine hesitancy in Europe. Ten thematic categories were identified across the 103 articles which were included in the review. Participants from European studies most commonly reported issues with the quantity and quality of information available about HPV vaccination; followed by concerns about potential side effects of the vaccine; and mistrust of health authorities, healthcare workers, and new vaccines. Comparative analyses indicated that confidence determinants differed by country and population groups. This evidence supports the need to develop context-specific interventions to improve confidence in HPV vaccination and design community engagement strategies aiming to build public trust.