A tale of two paths to vaccine acceptance: self-interest and collective interest effect, mediated by institutional trust, and moderated by gender

The study examines how individual motivators—collective interest (altruism) versus self-interest (egoism)—shape attitudes toward COVID-19 vaccination. Drawing on expectancy-value theory, the authors posit that people act in line with expected valued outcomes: collectivistic orientations should increase vaccine-supportive attitudes, while egoistic orientations should reduce them. The work also addresses the role of institutional trust, proposed as a mediator linking these motivators to vaccine attitudes, and investigates gender as a moderator based on the selectivity hypothesis, which suggests women process information more comprehensively than men. Conducted in Israel, where vaccination campaigns were strongly promoted, the study aims to clarify inconsistent prior findings on institutional trust by testing a moderated mediation model of vaccine attitudes.

Prior research links collective interest to prosocial and preventive health behaviors, including vaccine acceptance, and self-interest to more independent, less cooperative behaviors. Evidence suggests altruistic messaging is more persuasive during crises, and interdependent (collectivistic) individuals cooperate more in pandemic-related measures. Institutional trust has been identified as a key correlate of vaccination intentions and belief in accurate health information, and can mediate effects of information and social identity on vaccine intentions. The selectivity hypothesis indicates women engage in more comprehensive information processing and show higher risk concern, implying that trust built via broader information processing could more strongly affect women’s vaccination attitudes. These streams support hypotheses that collective interest positively and self-interest negatively affect vaccine attitudes (H1, H2), that institutional trust mediates these relationships (H3a, H3b), and that gender moderates the mediation (H4a, H4b), with stronger effects for females.

Design and setting: Cross-sectional survey administered online in Israel via the Blueberries access panel. Ethical approval obtained from Ariel University; informed consent secured. Sample: N=464 Israeli adults aged 18–57 (M=36.5, SD=10.7); 56% female, 44% male. Most had postsecondary education (75%); 57% reported average income or above. The focus on ages 18–57 targeted a group with lower but non-negligible COVID-19 risk and relatively higher vaccine hesitancy. Measures: All items used 7-point Likert scales (1=strongly disagree to 7=strongly agree). Attitude toward vaccination (5 items; adapted from Fu et al., 2015; two reverse-coded); Institutional trust (7 items; based on Ervasti et al., 2019; Zimand-Sheiner et al., 2021) covering trust in legal system, police, government, local authorities, health system, medical insurance, and military; Collective interest (4 items; Price et al., 1995); Self-interest (4 items; Birch et al., 2018). Demographics collected. Validation: Confirmatory factor analysis indicated good fit: χ²(150)=448.15, p<0.05; χ²/df<3; CFI=0.951; NFI=0.929; RMSEA=0.066. Standardized loadings >0.50; AVE/CR supported convergent validity (Attitude AVE=0.63, CR=0.89; Institutional trust AVE=0.57, CR=0.90; Collective interest AVE=0.65, CR=0.88; Self-interest AVE=0.64, CR=0.87). Discriminant validity supported via AVE>MSV. Analysis: Two moderated mediation models (PROCESS Model 14 with 20,000 bootstraps) were estimated separately: (1) collective interest as predictor with self-interest as covariate; (2) self-interest as predictor with collective interest as covariate. Institutional trust was modeled as mediator; gender as moderator of the trust→attitude path.

Measurement: CFA supported reliability and validity (CFI=0.951; RMSEA=0.066; AVE: 0.57–0.65; CR: 0.87–0.90). Collective interest model: Direct positive effect on attitudes (B=0.15; t=2.45; p<0.05). Collective interest positively predicted institutional trust (B=0.19; t=3.30; p<0.01). Institutional trust positively predicted attitudes, stronger for females (B=0.49; t=7.45; p<0.01) than males (B=0.27; t=3.56; p<0.01). Gender×trust interaction significant (B=0.22; t=2.18; p<0.05). Moderated mediation supported: index B=0.04; 95% CI [0.01, 0.10]; conditional indirect effects—females: 0.09 (95% CI [0.03, 0.17]); males: 0.05 (95% CI [0.01, 0.10]). H1, H3a, H4a supported. Self-interest model: Direct negative effect on attitudes (B=-0.15; t=-2.77; p<0.01). Self-interest positively predicted institutional trust (B=0.16; t=3.29; p<0.01). Institutional trust→attitudes stronger for females (B=0.49; t=7.45; p<0.01) than males (B=0.27; t=3.56; p<0.01). Gender×trust interaction significant (B=0.22; t=2.18; p<0.05). Moderated mediation supported: index B=0.04; 95% CI [0.01, 0.09]; conditional indirect effects—females: 0.08 (95% CI [0.02, 0.14]); males: 0.04 (95% CI [0.01, 0.08]). H2, H3b, H4b supported.

Findings confirm two pathways from personal motivators to vaccine attitudes. Collective interest aligns with more favorable attitudes both directly and indirectly via institutional trust. Self-interest directly reduces favorable attitudes, but trust in institutions generates a countervailing positive indirect path, indicating that trusted institutions can temper egoistic tendencies regarding vaccination. Gender moderates the trust–attitude link: consistent with the selectivity hypothesis, females’ more comprehensive information processing and higher risk concern strengthen the impact of institutional trust on vaccine attitudes. This helps explain prior mixed findings and underscores the centrality of institutional trust and gendered information processing in shaping vaccine acceptance.

The study advances understanding of vaccine attitudes by integrating individual motivators with institutional trust and gender. It shows that collectivistic orientations promote, and egoistic orientations hinder, positive vaccine attitudes; however, institutional trust mediates both effects, with a stronger influence among females. Theoretically, the work extends expectancy-value and self-construal perspectives by demonstrating a moderated mediation pathway through institutional trust and gender. Practically, it suggests building and maintaining institutional trust can enhance vaccine acceptance—especially among women—and that communication should be tailored to gendered processing styles. Future research should examine these mechanisms across different vaccines, populations, and cultural contexts, and assess how prior vaccination experiences shape these relationships.

The cross-sectional survey was conducted post-pandemic when many respondents had prior vaccination experiences, which may have influenced attitudes. Generalizability beyond COVID-19 vaccines is uncertain; testing with other vaccines (e.g., influenza, HPV) is needed. The focus on gender warrants broader intersectional analyses (age, education, ethnicity), and cross-national studies could clarify contextual differences. Longitudinal designs would better capture the development of institutional trust and its effects over time.