In this study, we used Google Trends data to conduct a chronological and geographical analysis of specific HPV terms to understand relative public concern. Overall Japanese public search interest in “cervical cancer,” “HPV vaccine,” and “cervical screening” phrases increased between 2010 and 2013. Subsequently, interest in “cervical cancer” and “cervical screenings” remains stable while “HPV vaccine” decreased in volume. In 2020, the public reignited its interest in “HPV vaccine” rather than “cervical cancer” or “cervical screening.” In relation to the actual annual number of cervical cancer cases, the search interest in “cervical cancer” and “cervical screening” showed a strong correlation, but “HPV vaccine” did not. Our results provide quantitative evidence that public interest coincides with government policy by change points detected around 2010, 2013, and 2020. Prefectures exhibited different search interests for these topics. We examined the chronological changes and geographical differences in cervical cancer and its related terms using public search engine interest. We believe that Google Trends can provide a unique perspective for policymakers and professionals alike.
Japan has been experiencing an HPV vaccine crisis that started in 2013 with a rapid decline in vaccination rates. When correspondingly low coverage of vaccination rates was < 1%, public search interest in “HPV vaccine” also maintained a low search volume. From 2013 until 2020, the MHLW suspended its proactive HPV vaccine recommendation campaign. Positive articles became less frequent than negative articles, following negative impacts from mass media reporting [12], which negatively affected Japanese mothers’ intentions to vaccinate their adolescent daughters [31]. The WHO also commented that this policy decision based on weak evidence led to a lack of vaccine administrations, resulting in real harm [32]. Subsequently, evidence has shown that HPV infection rates rose again [7], which resulted in a persistently high burden of disease, despite being preventable [6].
Fortunately, the MHLW announced a proactive recommendation for HPV vaccination again in 2021. From our findings, this policy reignited the public interest. We expect this nationwide HPV vaccine reintroduction to better control cervical cancer, achieving the target set by the WHO for a 90% coverage rate for girls by 2030 [33]. In contrast, search interest in “cervical cancer” and “cervical screening” maintained a stable and relatively high volume and was strongly correlated with the number of actual cancer cases. However, interest volumes of “cervical screening” are far less than for “cervical cancer.” In real-world situations, women receive a low percentage of cervical cancer screenings, despite the increase in cancer prevalence [34]. Only 22.2% of women in their 20s underwent cervical cancer screenings in Japan, this is comparatively low to other developed nations [35].
From 2013—2021, we detected three critical time points (2010, 2013, and 2020) for public interest in cervical cancer. In 2009, the HPV vaccine was licensed and it was publicly subsidized in 2010. In 2013, the MHLW withdrew their proactive recommendation for the HPV vaccine, due to sensationalized media reports of adverse events. In 2020 and 2021, several vote campaigns related to the HPV vaccine were organized by Change Japan, which is an online signature site used by 400 million people worldwide [36]. The campaign “Call for the resumption of proactive HPV vaccination recommendations” was lunched on August 27, 2021 and endorsed by 58222 people. In addition, the MHLW revisited the safety of the HPV vaccine and resumed its recommendation. In 2017, the Japan Expert Council on Promotion of Vaccination, a body of 17 academic societies from a broad range of fields, sought a strong endorsement for HPV vaccination [37]. In 2019, the Liberal Democratic Party (LDP) in Japan took up this challenge and launched a parliamentary league to actively promote HPV vaccination recommendations [38]. However, the public did not show increased interest in “cervical cancer” in 2017 or 2019, as search interest trends did not change. Effective information dissemination has been proven to promote public health. Authorities can refer to search data to understand the local public response to events in real-time and facilitate rapid adjustment of promotional strategies.
Geographical search volumes for “cervical cancer,” “HPV vaccines,” and “cervical screening” showed disparities. Hokkaido and Osaka prefectures showed more public interest in “cervical cancer” and “cervical screening,” but not in “HPV vaccine.” Kyoto, Okayama, Kumamoto, Tokushima, Nara, and Yamanashi prefectures were more interested in “HPV vaccine.” Those subregions with low search volumes for “HPV vaccine” included Fukushima, Saga, Okinawa, Wakayama, and Aichi prefectures. In addition, subregions including Ishikawa, Tottori, Kyoto, Shizuoka, and Nagano prefectures displayed low interest in “cervical screening.” Relevant authorities should enhance dissemination of HPV vaccine and cervical cancer awareness in these sub-regions. Encouragingly, in the latest briefing on HPV vaccination, the MHLW recommended cooperation among regions and the establishment of consultants to promote vaccination [39]. Although search interest in “cervical cancer” and “cervical screening” was strongly correlated with the actual number of cervical cancer cases, we did not find a similar situation for the subregion interests. We speculated that this might be attributed to a deviation in regional-level searches from locations where cervical cancer was diagnosed. Nevertheless, Google Trends search data still serves as a useful tool for understanding the public interest for a particular topic in different subregions.