This study aimed to examine the profile of vaccine-hesitant people in nine countries in the WPR by conducting LCA. Our analysis identified six latent subgroups:college students, HCP distrusters, stay-at-home mothers, the elderly, and compliant pragmatists, and general working population, among which three groups - college students, HCP distrusters, stay-at-home mothers – were less likely to accept COVID-19 vaccines and less likely to receive a booster vaccine shot than the other groups. Mapping out variations in the profiles of vaccine-hesitant people across the region, we categorized the countries into several categories to provide more tailored recommendations for addressing vaccine hesitancy.
The overall discussion of this study contributes to the vaccine literature by demonstrating the diversity in the profile of vaccine-hesitant populations across WPR using a subgroup approach. It has become almost axiomatic that vaccine hesitancy is a multidimensional problem;24,25 yet, many countries in the WPR have been underrepresented in the literature.29,32 The diverse profiles of vaccine-hesitant people in the WPR illustrated in Figs. 3 and 4 confirm that vaccine hesitancy in the region reflects the complex and diverse historical, cultural, and political landscapes of each country. There is a need for more data and research on countries that are still underrepresented in the literature.
The study findings can inform international and national policymakers in customizing interventions to tackle vaccine hesitancy. Figures 3 and 4 imply that there are three primary target groups on that WP countries should focus. First, in countries where HCP distrusters took a large portion of people who had not gotten a booster COVID-19 vaccine, especially in Cambodia, Japan, Lao PDR, Malaysia, and PNG, rebuilding public confidence in vaccines, the health care system, and the government is necessary to promote COVID-19 vaccines. Governments in these countries should make extraordinary efforts to be transparent, share timely information, and engage the public when promoting vaccines.39 Moreover, causes of mistrust in institutions are notably contextual and vary by country. For example, mistrust in HCPs is likely to be rooted in the fragmented political system in PNG, where the political mistrust in the central government is generally high among thousands of tribes,28 while, in Japan, it may reflect the historical vaccine hesitancy developed from the Measles, Mumps, and Rubella (MMR) vaccine scandal in the 1990s and the human papillomavirus (HPV) scandal in 2013.40 Therefore, additional efforts to understand the root causes and histories of mistrust should be in tandem with the efforts to rebuild trust in these countries.
Second, the Philippines had a profile of vaccine-hesitant people that is somewhat distinct from that of other countries, where stay-at-home mothers represented a large portion of people without a booster vaccine shot. More than one hundred children died in the Philippines as a consequence of the Dengvaxia scandal, resulting from the inappropriate administration of vaccines against Dengue fever.26,27 Prior studies found that low-risk perception of COVID-19 and concerns over vaccine safety and side effects are highly influential barriers for parents in vaccinating their children.41–43 Furthermore, recent studies observed that social media information has a growing impact on the vaccination choices of mothers and women of childbearing age.42,44 Thus, measures to increase mothers’ understanding of the safety of vaccines may be beneficial in the Philippines. In our case, stay-at-home mothers were more likely than other groups to believe that the government was not responding effectively to the COVID-19 pandemic, but to have trust in local HCPs. Therefore, vaccine-related messages or campaigns involving local HCPs may be a more effective means of combating vaccine hesitancy in the Philippines.
Lastly, in Mongolia, the ROK, and Viet Nam the general working population represented the largest proportion of the vaccine-hesitant population. As explained, this subgroup was the least vaccine-hesitant, among the identified subgroups, with a higher level of trust in local HCPs. Moreover, these countries have not suffered vaccine-related scaldals and have a higher income-level than other participating countries. The vaccination rate has also been sharply growing over the past year in these countries.45 Therefore, these countries should pursue policy efforts that maintain the current status of public trust in government and medical establishments. Meanwhile, they could focus on consistent messaging from public health authorities while continuously monitoring possible risk factors for vaccine hesitancy, such as the spread of misinformation, instead of instituting a targeted strategy or campaign.
Our findings imply the existence of unobserved heterogeneity in the phenomenon of vaccine hesitancy conditional on typical demographic characteristics and further stress that continuous efforts should be made to identify and persuade hidden risk groups. Utilizing the LCA approach helped shed light on these under-researched patterns and further elaborated the profile of risk groups with low vaccine acceptance and uptake in each studied country. Our suggested recommendations for each country category may help policymakers develop customized vaccine communication strategies. More investigations and research are needed to develop more tailored interventions focusing on specific target groups. Only few empirical studies have been done focusing on developing countries and underrepresented populations, such as racial and ethnic minorities, in the WPR.32 Future studies should focus on these populations that have not received sufficient attention in the scientific community.
Limitations
This study has the following limitation. Our LCA approach estimated the maximum likelihood function at the regional level and then examined distributions at the national level. Therefore, the number of identified subgroups might not maximize the likelihood function for each country and may vary by country. Despite this limitation, the international comparison in this paper still provides useful insight on how to vaccine promotion strategies can be tailored based on the profile of vaccine-hesitant subgroups in the country by generating comparable latent classes.