Identifying the intentions and interests of the user through their search queries would be effective in providing more relevant results to the userten. We initially assumed that people who searched for “vaccination appointment” or “vaccination appointment” were proactive in their attitudes towards vaccination. For these users, prioritizing information about vaccination locations and reservations as search results may have been facilitated by their use of Internet search engines. On the other hand, we assumed that “adverse vaccine reactions” would likely be sought by people who were skeptical of the vaccine. Yet when we looked at the correlation between ICV and vaccination rate11as shown in Figs. 1a,c, we found a significant positive correlation between prefecture rank based on VCI and prefecture rank based on vaccination rate (Spearman’s (rho) = 0.60, (p ): the higher the VCI, the higher the vaccination rate (as of August 31, 2021). This suggests that prefectures more concerned about vaccinations and adverse effects were also more likely to have higher vaccination rates.
A possible interpretation of these results could be that people who seek information on adverse effects may be hesitant to get vaccinated, but the hesitation does not mean that these users have decided not to get vaccinated: on the contrary, research “adverse vaccine reactions” could be part of the individual’s information-gathering process before deciding whether to accept or avoid vaccination. If so, providing users with appropriate information (as opposed to misinformation) about adverse reactions can help guide these decision-making processes in a constructive way, which may eventually lead to greater acceptance of the vaccine in the community. society. Such an interpretation would be consistent with psychological research on persuasion.12, especially through the central (elaborative) pathway, providing individuals with sufficiently accurate information for decision-making. In this sense, the VCI could highlight cases of serious deliberation on the part of people who intend to be vaccinated or who have just been vaccinated, and who may be looking for adverse effects after vaccination. Conversely, people opposed to vaccination on moral or political grounds may be largely indifferent to adverse effects, and future research could focus on these terms as questions for understanding vaccine hesitancy.
As such, the relative placement of vaccine adverse event queries versus vaccine appointment queries could represent cognitive deliberation beyond a basic attitude toward vaccination, which is represented by requests for appointments: a person who is likely to request an appointment may search for vaccines once or twice when making an appointment, but a person who is worried and who is planning to get vaccinated may check for adverse side effects repeatedly until a satisfactory conclusion is reached (or until the adverse effects disappear after vaccination).
Analysis of VCI results by prefecture
Overall, prefectures with a low VCI tended to have a relatively smaller older population and a larger younger population. Saitama in Kanto region (R3), which has the sixth lowest VCI as shown in Table 1 and the fifth largest population, conducted online surveys on attitudes towards COVID vaccination -19 among young people aged 18 to 39 in August 202113. 70.3% of the respondents answered either “vaccinated at least once”, “will definitely get vaccinated” or “probably will get vaccinated”, suggesting that the inhabitants of this prefecture have a positive attitude towards vaccination. The survey in Saitama was conducted during the same time period that our selected search queries were actually searched the web, and we found consistent results, in that young people seem less concerned about vaccinations than other age groups. This can help contextualize our findings, as other low-VCI prefectures also tend to have large populations and high percentages of young people. It could be that these younger people are not as concerned about vaccine side effects and therefore are less resistant to vaccinations.
On the other hand, Fukushima in Tohoku region (R2) has the lowest VCI even though its population is lower than other prefectures, as shown in Figs. 1a, b. In Fukushima, the number of recorded infections was high in early August 2021, and in response, priority measures to prevent the spread of the disease were declared. Priority measures to prevent the spread of the disease are legal measures issued by the government for specific areas to prevent the spread of the disease before a state of emergency is declared. In more populated prefectures such as Kanagawa and Chiba, where the VCI is low, a state of emergency had already been declared. Although it is not a highly populated prefecture, the government’s statement following other highly populated prefectures may have influenced people’s attitudes towards COVID-19 and vaccination.
On the other hand, Gunma is the only prefecture in the Kanto region (R3) with a VCI greater than 1. This indicates that the use of requests for vaccination appointments is lower in Gunma than in the other prefectures in the region. of the Kanto and that vaccination is not actively sought. . The Kanto region is the most populous region in Japan, with the population of four prefectures of Tokyo, Kanagawa, Saitama and Chiba accounting for 30% of the Japanese population (Fig. 1a,b). Compared to these prefectures, Gunma has a small population. However, VCI is less than 1 in Tochigi, which has a similar population to Gunma. This suggests that there may be trends other than population that are unique to Gunma.
Analysis of VCI results by age and gender
Our results show that female users have a higher VCI than male users, especially those in their 20s to 40s. Okubo et al. conducted a survey to examine the proportion of vaccine hesitancy against COVID-19 and factors associated with vaccine hesitancy in Japan6. In their survey, 26,000 people from all prefectures in Japan participated in an online survey conducted in February 2021. The results show that the proportion of vaccine hesitancy is particularly high among young people, women and people living alone. Despite the time difference, our results show a similar trend to Okubo et al.’s survey, in that we found that women aged 15-39 made up the highest proportion of users who avoided the vaccination. One of the reasons for these results could be the spread of misinformation on the Internet that vaccination causes infertility14.15. The Japanese Society of Obstetrics and Gynecology recommends vaccination, but says more information needs to be gathered on medium- and long-term safety16. Women who are exposed to this information are more likely to be cautious about vaccination, which is reflected in the survey results.
The VCI is below zero for users over 60, indicating that the percentage of searches with queries about adverse vaccine reactions was lower than other age groups. This is not surprising, given that adults over 65 have higher rates of serious illness and death with COVID-19 infection.17.18. As a result, vaccination of people over 65 was prioritized and vaccinations started in April 2021 in Japan. The study by Okubo et al. also found that the proportion of vaccine hesitancy was more than twice as high among young people aged 15 to 39 as among people aged 65 to 79. There are several possible reasons for the decline in concerns about vaccination among the elderly. For example, studies of the safety and effectiveness of the COVID-19 vaccine have reported that older people are less likely to have adverse effects than younger people.19.20. This result could be a consequence of our choice of “adverse reactions to vaccines”. Alternatively, older users may not be used to searching for terms and queries on topics relevant to them.
Cultural background of vaccine concern
As a collectivist and Confucian culture, the Japanese often have an interdependent view of self21, which means that personal freedoms are given lower priority than actions that benefit society. In this regard, vaccination is seen as a prosocial activity “for the greater good”22, and guidelines issued by authoritative figures (e.g., medical professionals, government), on policies such as vaccination, become a widely followed social norm. As a result, concerns about vaccine acceptance lean towards a practical nature, such as considerations of side effects and physical risk, and less of a moral or ideological stance (as in individualistic cultures like the United States). Our study is therefore consistent in that VCI is able to quantify these practical considerations in the decision-making processes of Japanese individuals. Since such “greater good” arguments are common to collectivist and Confucian cultures in East Asia (e.g., China, South Korea), the VCI may therefore be adaptable to these comparable cultural contexts for the infodemiological measure of concern and hesitation vis-à-vis vaccines.