Attitudes toward Vaccinations Are Becoming More Polarized in New Zealand: Findings from a Longitudinal Survey

"With increasing confidence among former skeptics and decreasing confidence among vaccine skeptics, our findings indicate that vaccination attitudes are becoming increasingly polarized in New Zealand."

With the recent increase in anti-vaccination movements and dissemination of anti-vaccine information, public concern about vaccine safety seem to be on the rise. In New Zealand, at each of the milestone ages, 4.3 to 5.4% of parents declined any one vaccination during the year 2019; concerns about the risk or side effects of vaccinations are frequently cited as one of the main reasons for incomplete immunisations. Using survey data across 4 waves of the New Zealand Attitudes and Values Study (NZAVS), this study examines whether the New Zealand public collectively exhibits decreasing or steady vaccine confidence over time, or whether there are distinct subpopulations with diverging trajectories of confidence.

The study uses NZAVS Time 5 (2013), Time 7 (2015), Time 8 (2016), and Time 9 (2017) data, which included an item on vaccine confidence. The number of responses included from Time 5, 7, 8, and 9 were 12,423, 11,912, 12,009, and 10,254, respectively. Time 9 (most recent time point) showed that most participants reported that their children were "fully vaccinated" (87.6%), followed by "partially vaccinated" (6.1%) and "unvaccinated" (2.9%). Maori reported the highest percentage of unvaccinated children (4.0%).

Table 2 clarifies the definitions of key terms and groups labels used in this study. Table 3 reports the intercept (indicating group level of vaccine confidence in 2013) and slope (indicating the trend in confidence over time) for each of the 3 subpopulations with distinct rates and directions of change in vaccine confidence:

• "Vaccine (safety) believers": The largest subpopulation (N = 7,784, 60.7% of sample) was characterised by consistently high and subtly increasing belief in vaccine safety over time.
• "Vaccine (safety) skeptics": Making up 29.6% of the sample (N = 3,792), this subpopulation is becoming increasingly concerned about vaccine safety over time.
• "Former (safety) skeptics": The third subpopulation (N = 1,249, 9.7% of sample) initially had low vaccine confidence in 2013 (3.47) but are becoming increasingly confident over time. By 2017, their confidence rating reached 5.88.

Looking at the demographic profiles of subpopulations, vaccine skeptics were more likely to be women (odds ratio (OR) = 0.66), of Maori (OR = 1.99), Pacific (OR = 1.58), or Asian (OR = 1.41) ethnicity, to live in more deprived regions (OR = 1.06), and to have lower education (OR = 0.89).

Reflecting on the findings, the researchers suggest that a wide range of factors are likely contributing to the maintenance of strong vaccine confidence among vaccine believers. Based on previous studies, vaccine believers may be those who have satisfactory access to vaccine information, strong trust in health professionals, and better knowledge regarding the risk of vaccine-preventable diseases and the benefits of and social responsibility associated with vaccinating. In contrast, vaccine skeptics may represent those who lack access to adequate healthcare, have inaccurate or insufficient vaccine knowledge, or negative perceptions of health professionals. Due to limited access to trusted sources of vaccine information, their doubts about vaccine safety may not have been sufficiently addressed by health professionals and further exacerbated by exposure to anti-vaccine sentiments.

Studies cited here have shown that health professionals have important influence on vaccination attitudes and uptake; satisfactory follow-up vaccine conversations with doctors may have led former skeptics in New Zealand to reconsider and gradually change their views of vaccine safety. The 2014 measles outbreak may have been a key event that encouraged these individuals to seek further vaccine information and consult health professionals. In contrast, vaccine skeptics may have limited knowledge about the risk of measles and lack the opportunities or capability to reassess their vaccine beliefs. Such discrepancies can be linked back to potential differences in healthcare access and trust in health professionals between subpopulations.

Disparities in healthcare access, perceptions of health professionals or vaccine knowledge are closely tied to one's demographic characteristics. For example, for those of Maori or Pacific ethnicity and from highly deprived regions, low healthcare access may be a key contributing factor to their higher likelihood of being a vaccine skeptic or former skeptic. These groups typically experience greater financial or transport related barriers to healthcare and difficulty communicating with health providers due to language or cultural differences. They are thus less likely to have sufficient access to vaccine information, feel well-informed, or have high-quality vaccine conversations with doctors. Among these groups, those who were able to have their initial vaccine concerns addressed by culturally competent health professionals may be showing increasing confidence, while those who lacked this opportunity or do not trust their health professional persistently express growing concern.

As women typically make decisions regarding their child's vaccination, they are more inclined to do additional vaccine research and feel anxious about making the right decision for their child. Consistent with findings from an American sample, perhaps New Zealand women are also more likely to trust non-professional sources of vaccine information than men. Women who remain skeptical may be swayed by anti-vaccine information and unsatisfied with their providers' ability to address their concerns. As suggested here, to effectively convince these women, health professionals need to go beyond simply providing pro-vaccine information: They need to take the time to understand the specific concerns and sources of misinformation among skeptical women, and use easily-understood language to communicate evidence-based data to correct any misconceptions they hold.

With regard to the finding that low education is an important contributor to decreasing confidence among vaccine skeptics, the researchers suggest that this subpopulation may be more likely to endorse anti-vaccine conspiracy theories but lack access to trusted sources of vaccine information that can correct their misconceptions. In contrast, those who are more educated may be better able to understand and communicate with their doctor and thus more likely to trust in health professionals and the safety of vaccinations they recommended. Parents with higher education were found more likely to have fully vaccinated children, further highlighting that parental education is a crucial contributor to both vaccine confidence and uptake among New Zealanders.

In conclusion, although the majority of New Zealanders consistently exhibit strong vaccine confidence, 30% show steadily decreasing confidence over time. Thus, "It is imperative to develop tailored interventions for groups at higher risk of low vaccine confidence." Suggestions offered here include improving healthcare access for low socio-economic groups, implementing educational campaigns on vaccine safety, and interpreting vaccine information for those with low education. "Moreover, health professionals need to be sufficiently trained to develop trusting relationships with and adequately address vaccine concerns among diverse groups, especially young mothers and ethnic minorities. To better identify specific strategies to effectively persuade vaccine skeptics, it is vital to further investigate the key facilitators of attitude change among former skeptics."