Addressing the Vaccine Hesitancy Continuum: An Audience Segmentation Analysis of American Adults Who Did Not Receive the 2009 H1N1 Vaccine

"Although individuals were traditionally considered to be 'pro'- or 'anti'-vaccination, such a dichotomous characterization masks variation and results in missed opportunities to develop customized communication strategies and reach large groups who may be open to vaccination."

In the context of the H1N1 pandemic response of 2009-2010 in the United States (US), this study examines the potential of using audience segmentation techniques to identify subgroups of vaccine-hesitant individuals and plan for effective engagement. In March 2010, the researchers surveyed 1,569 respondents, drawn from a nationally representative sample of American adults, with oversampling of racial/ethnic minorities and persons living below the US federal poverty level. Guided by the Structural Influence Model (SIM), they assessed knowledge, attitudes, and behaviours related to H1N1, communication outcomes, and social determinants among 3 subgroups of individuals who did not receive the H1N1 vaccine: the Open to Persuasion, Informed Unconvinced, and Disengaged Skeptics clusters.

The 2009 H1N1 influenza virus emerged and began to spread rapidly across the US in April of that year. This resulted in a wide-scale emergency response that emphasised activation of public health preparedness systems, as well as education of the general public regarding this strain of influenza, risks of contracting the virus, and key prevention strategies, including vaccination. At the outset of the pandemic, approximately half of the public reported they would receive the vaccine; however, by April 2010, only 24% of adults had received the vaccination, well below the rates of regular seasonal influenza vaccination. As explained here, the drivers of vaccine hesitancy are diverse, including contextual influences (such as culture, healthcare systems, political structures), individual and social group influences (such as norms, beliefs), and vaccine- and vaccination-specific issues. In the case of vaccines perceived by the public to be novel, like H1N1, hesitancy may include concerns about safety, side effects, disease severity, the rapid vaccine development process, and financial incentives for vaccine producers.

"Despite public concerns, governments and public health agencies must act quickly and effectively to stop pandemic influenza strains from having massive impacts across the globe. Beyond vaccine production and distribution, a major tool in their arsenal is communication. Yet, officials and authorities often utilize a top-down, expert-led approach, with a generic, one-size-fits-all approach....Such approaches are unlikely to lead to behavior change across population sub-groups. A multi-pronged effort, involving interactive dialogue, interpersonal and mass media communication, and public engagement is likely necessary to support individuals in making decisions about vaccines that are evidence-informed....Such an effort requires understanding the diverse audiences along the vaccine hesitancy continuum for whom communication/engagement campaigns must be created."

The SIM posits that inequalities in communication (such as differential exposure to information for population subgroups) mediate the relationship between social determinants (such as socioeconomic position, race/ethnicity, or other factors) and health outcomes, thus serving as one potential explanation for health disparities. In other words, health disparities can be understood in part as a function of how (1) structural determinants such as socioeconomic position and (2) moderating mechanisms such as social networks lead to (3) differential communication outcomes, such as access to and use of information channels, attention to health content, recall of information, and capacity to act on relevant information, which in turn drive (4) awareness/knowledge, risk perception, preventive behaviours, and other emergency preparedness behaviours. For this segmentation analysis, the researchers applied the framework (pictured in Figure 1 of the article) by working from the endpoints (Public Health Emergency Preparedness (PHEP) outcomes) backwards to understand the link between audience segments and key theoretical drivers of outcomes of interest.

Using the SIM as a theoretical framework, the researchers developed 3 research questions: (1) What are the key audience segments among individuals who did not receive H1N1 vaccination based on key PHEP outcomes (awareness/knowledge, risk perception, and preventive behaviours)? (2) Were there significant differences between audience segments in communication outcomes (information access, use, and exposure; information-seeking; and trust/credibility)? (3) Were there significant differences between audience segments in social determinants (socioeconomic position (SEP), race/ethnicity, immigrant/nativity status, and place)?

Among those who did not receive the vaccine (n = 1,166), cluster analysis identified 3 vaccine-hesitant subgroups:

• Disengaged Skeptics (67%) were furthest from vaccine acceptance, with low levels of concern and engagement. Only about 10% of members of this cluster indicated an intention to get the H1N1 vaccine. The group reported low risk perception related to H1N1 and relatively lower perceptions of H1N1 vaccine safety. Key barriers to H1N1 vaccination included low risk perception, concern about side effects, and a lack of trust in public health officials. This group had somewhat lower trust in their primary source of H1N1 information, lower attention to H1N1 news, and less information-seeking related to H1N1 than the other clusters. They relied more heavily on local television news than the other groups. From a demographics standpoint, this group included more of the young respondents, included large numbers of white, non-Hispanics and Hispanics, had a lower percentage of women, and had the highest percentages of working adults compared to the other clusters. In terms of communication strategies, this group may have needed to be brought along slowly regarding more than just the H1N1 vaccine.
• The Informed Unconvinced (19%) were sophisticated consumers of media and health information, with the highest reported internet access, who nonetheless may not have been reached with information to motivate vaccination. This cluster was characterised by 21% indicating intention to receive the H1N1 vaccine, despite the fact that all of the individuals in this group reported receipt of the seasonal flu vaccine. As a group, they were relatively moderate in assessing risk of contracting H1N1 and vaccine safety. In addition to local and national network news, they relied on healthcare professionals as primary sources of H1N1 information. The top reason for not getting the H1N1 vaccine in this cluster was not being part of a priority group. This group had the highest income levels, the largest proportion of white, non-Hispanic individuals, the highest proportion of US-born individuals, and the highest proportion of women. A large portion of the group was retired or not working for other reasons. The communication strategies targeting such a group may need to address a high level of knowledge and potential skepticism related to this disease and vaccine specifically.
• The Open to Persuasion cluster (14%) had the highest levels of concern and motivation and may have required engagement about vaccination broadly. This group had lower risk perception than the other groups and more moderate perceptions about vaccine safety. They engaged in a higher number of correct preventive behaviours than the other groups. They paid a great deal of attention to H1N1-related news and had much higher rates of information-seeking than the other clusters. In addition to local and national network news, they relied on healthcare professionals as primary sources of H1N1 information. Demographically, they tended to have lower income levels and greater proportions of Hispanics, individuals from homes in which Spanish was the primary language, and individuals born outside of the United States. There may have been an opportunity to address the needs of this group and increase vaccination rates.

In line with the SIM, these findings "highlight the critical roles played by communication and information in vaccination decisions, which can provide an opening to engaging with the diverse segments of the public along the vaccine hesitancy continuum for a given vaccine. Use of a health behavior or health communication theory to drive the segmentation analysis allows for effective targeting of key variables to promote behavior change....In addition to strategic methods of reaching diverse clusters of the vaccine-hesitant individuals, it is vital to ensure that communications focus on engagement and informed decision-making."

The researchers suggest that "The audience segmentation analysis demonstrated here may be useful in a range of settings. This assessment was conducted at the national level, but the approach could be applied at local or regional levels as well. Fielding the survey was both cost-effective and efficient with the use of an online panel....Further research efforts to use this approach to inform targeted public engagement strategies may unearth additional sub-groupings among the vaccine-hesitant. Additional segmentation studies focused on a range of vaccines will also allow for deeper understanding of the common and vaccine-specific aspects of hesitancy."