Immune response and intergroup bias: Vaccine-induced increases in cytokine activity are associated with worse evaluations of resume for Latina job applicant

• Published in: Brain, behavior, and immunity behavior, and immunity, 2024-11, Vol.122, p.555-564
• Main Authors: Makhanova, Anastasia, Tolliver, Mikayla D.M., Buckner, Zach, Shields, Grant S., Hunter, Colton L., Mengelkoch, Summer, Houpt, Joseph W., Belote, Alex E., Hoose, Dalton V., Schulz, Thomas K.
• Format: Article
• Language: English
• Subjects: Behavioral immune system; Cytokines; Hiring discrimination; Intergroup bias
• ISSN: 0889-1591; 1090-2139; 1090-2139
• DOI: 10.1016/j.bbi.2024.08.039

•Interleukin-1β (IL-1β) increased after influenza vaccine but not placebo injection.•Greater IL-1β increase after vaccine was linked to more intergroup bias.•IL-1β change was negatively associated with evaluation of Latina applicant’s resume.•IL-1β change was positively associated with ethnocentrism.•Findings suggest that working while sick may contribute to disparities in hiring. Situational factors can increase people’s vulnerability to intergroup bias, including prejudicial attitudes, negative stereotyping, and discrimination. We proposed that increases in inflammatory activity that coincide with acute illness may represent a hitherto unstudied situational factor that increases intergroup bias. The current study experimentally manipulated increases in inflammatory activity by administering the seasonal influenza vaccine or a saline placebo. We quantified inflammatory activity by assessing change in salivary pro-inflammatory cytokines and assessed intergroup bias using a resume evaluation task and self-reported ethnocentrism. Primary analyses focused on a subsample of 117 participants who provided high quality data; robustness analyses included various permutations of lower quality participants. Findings revealed that changes in the cytokine interleukin-1β (IL-1β) in response to the vaccine were associated with greater intergroup bias. Among participants who received the vaccine, IL-1β change was negatively associated with evaluation of a Latina (but not a White woman) applicant’s competency and recommended starting salary. Moreover, IL-1β change was positively associated with ethnocentrism. Overall, results provide support for the hypothesis that acute illness, via the mechanistic role of inflammatory cytokines, affects social cognition in ways that can increase intergroup bias.