Introduction of the HPV-vaccine in Denmark
After a successful launch of the HPV-vaccination programme, the vaccination uptake remained high for 6 years, after which we saw a decline. In this paper we describe the events leading up to the decline and focus on the potential correlation with media coverage and on-line search activity as a proxy of public attention. Our analysis of the correlation shows a change in the relation between the media coverage and vaccination uptake in July 2013.
The findings could indicate that as media attention increased, the public confidence in the safety of the vaccine decreased, and accordingly, vaccination uptake was reduced. The situation was self-perpetuating with a continuous stream of news-stories describing the decline in HPV-vaccination uptake and suggesting fear of adverse events as leading explanation. Media coverage related to the HPV-vaccination increased from 2012 and peaked in June 2013. Initially, the media attention was focusing on the benefits of vaccination, i.e. cancer prevention, which was also reflected in the annotated articles (see Fig.
3) and coincided with an increase in search activity on HPV-vaccine (see Fig.
2). The decline in vaccination activity stabilised in 2014 but was accelerated after the airing of the documentary “The vaccinated girls” in March 2015. In the same period, the search activity on adverse events increased markedly, indicating a profound impact on the public risk perception of the HPV-vaccine. There was also a noticeable increase in the number of reported adverse events related to HPV-vaccination in Denmark from 2012 with 95 reports compared to 2015 with 821 reports [
4].
The effect of media coverage on vaccination uptake has been studied in other contexts. Influenza vaccination rates has been shown to increase after significant media attention to a severe influenza season in the US [
18]. Further, articles suggesting a link between the MMR vaccine and autism has been linked to a drop in MMR vaccination in the US [
6] and the UK [
19]. A recent Danish study on the correlation between media coverage and the MMR vaccine showed that controversies in the media coincided with a correlation between vaccination uptake and media coverage, indicating a potential relationship [
8]. Our hypothesis about the connection between increased adverse event reporting and media coverage is corroborated by other studies. Eberth et al. reported that media coverage and in particular internet search activity may stimulate increased adverse event reporting [
20]. Faase et al. found results suggesting adverse events reporting was not related to the HPV-vaccination but to the news coverage and internet search stimulating concerns [
21]. Dunn et al. used Twitter to derive media exposures and showed that HPV vaccination coverage was lower in areas with higher proportion of exposure for safety concerns, misinformation and conspiracies [
22].
The effect of case stories reported in the news has not only been seen in Denmark. In Ireland concerns are raised as fewer girls receive HPV-vaccine [
23,
24]. The Japanese government suspended their active recommendation of the HPV-vaccine in 2013 in response to unfounded fears about the safety profile. The decision is still unreversed despite a supportive declaration from the country’s Vaccine Adverse Reactions Review Committee [
25]. Apart from the withdrawal of the HPV-vaccine in Japan, it is our impression that no other country had yet to experience an HPV crisis as strong as in Denmark. However, the proportion of girls who completed the vaccination schedule in Ireland dropped to an estimated uptake of 50% for the first dose in 2016–17 [
26]. The fact that other countries had yet to experience an HPV crisis as strong as in Denmark makes an influence from non-Danish media sources on the vaccination choices less likely. Karafillakis et al. have investigated vaccine-safety scepticism and found, with the notable exceptions of France and Italy, that Western and Northern European countries express less concern about vaccine safety than Eastern and Southern European countries [
27].
Our data provide indirect insight into the decision process to vaccinate ones child. This decision is influenced by multiple factors, one of those being publications in the media [
28]. Media is part of shaping parents impressions of the safety of a vaccine, which is the largest concern parents have today regarding vaccines [
29]. A greater belief in the protection offered by childhood vaccines has been found to correlate with acceptance of HPV-vaccines [
30]. Parent socio-economical [
31] and social-environmental factors including cultural beliefs as well as social group norms may also play a role [
28]. This influence of social group norms could explain the rapid decline in vaccination seen in our study. Both individual factors, as well as social group norms, can be influenced by massive media coverage and impact parental vaccination choices through different pathways. In other countries, such as the UK and US, parental concerns over HPV-vaccination promoting promiscuity [
32]. This has not been a topic in the Danish debate [
33].
In addition to the previously mentioned factors, physicians play a pivotal role in the parental vaccination decision pathway. Daley et al. has reported that physicians attitudes and intentions of recommending HPV-vaccination promote successful immunization delivery [
34]. Gilkey et al. found that providers presented HPV as an “optional” vaccine that can be delayed [
35]. HPV-vaccination being the latest addition to the Danish vaccination programme places it in a vulnerable position since physicians perceive the most recently introduced vaccines in the programme to be less important compared with the former [
36].
Monitoring media activity and describing the effect of media coverage on vaccination may help to develop new approaches to reach and maintain the optimal vaccination uptake. This is also very important to keep in mind when planning the introduction of potential new vaccines into a childhood vaccination schedule. Listening to the public should be a fundamental element of any introduction of a new vaccine. Larsson et al. have constructed a communication model that envisions communication as integrating safety assessment and trust-building strategies [
37]. Bahri et al. showed how real-time global media monitoring could be used for enhancing communication proactivity and preparedness to support vaccine use [
38]. In Denmark, the National Health Authority together with the Danish Cancer Society and other stakeholders launched an informational campaign, 2017, using as the key platform a Facebook page where professionals engage with the public in a timely manner [
39]. The Facebook page also directs traffic to an information homepage
www.stophpv.dk [
40] with additional material. A similar multi-stakeholder approach has been successful in raising the uptake of HPV-vaccination in Ireland [
26].
Strength and limitations
Using the DDV, we are able to closely monitor the development in HPV-vaccination uptake on population level using person identifiable data on a real time scale [
7]. The validity of the DDV has previously been studied indicating a 3 percentage points underestimation [
41]. The reporting to the DDV has since been made mandatory and automatized which should improve the completeness of the register [
42]. Our study was ecological in its design, limiting the possibility of causal inference.
While the media archive used for the media coverage analysis covers all the major Danish news sources, it is still dynamically changing which might introduce a bias. The most vocal media in the HPV debate have been present in the archive throughout the study period and bias through changes in the database content should therefore be limited. It is evident from the case of the documentary “The vaccinated girls” that a lot of spin-off stories were published in the written media. A large percentage of Danish parents may have sought their information online or in social networks since 92% of Danes have access to the internet at home [
43]. Not having data on social media is a limitation in this study and is an area for further research. However, Mollema et al. identified a strong correlation between the number of messages on social media and online news articles, indicating that public opinion is reflected on these platforms and that the written media determine themes discussed on social media [
44].
We analysed the content of a sample of the media stories and found the results to confirm our prior perception of increasingly negative media sentiment (see Fig.
3). Previous studies have shown that just the mention of a controversy in the media may impact public awareness regardless of specific content [
45]. This paper is intended as a description of the events leading up to the decline in the HPV-vaccination uptake.