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Brain Behav Immun
. 2025 Apr 14:S0889-1591(25)00147-3.
doi: 10.1016/j.bbi.2025.04.018. Online ahead of print. Effects of a mild inflammatory challenge on cytokines and sickness behavior: A randomized controlled trial using the influenza vaccine
Tatum A Jolink 1 , Mallory J Feldman 2 , Natalie M Antenucci 3 , Megan N Cardenas 3 , Taylor N West 3 , Zev M Nakamura 4 , Keely A Muscatell 5
Affiliations
The influenza vaccine has reliably been associated with mild, within-person increases in inflammation. However, the field lacks rigorous experimental work comparing the effects of the influenza vaccine to a placebo control on changes in plasma inflammatory cytokines and self-reported sickness behavior. In a double-blind, randomized, placebo-controlled trial, 102 participants received either the influenza vaccine or saline placebo. Four cytokines were measured in plasma 24-hours following injection; participants also reported on psychosocial outcomes, specifically sickness behavior, positive/negative affect, sleep, and subjective social disconnection. All cytokines-IL-6, IL-10, TNF-α, IFN-γ-were significantly increased in the influenza vaccine condition compared to placebo. None of the psychosocial outcomes differed by condition. This study fills a gap in the literature by presenting critical causal evidence that the influenza vaccine leads to elevated levels of four inflammatory cytokines, compared to placebo control. However, a more robust increase in inflammation or a larger sample size may be necessary to observe differences in self-reported sickness behavior and other psychosocial outcomes.
Keywords: Affect; Inflammation; Influenza vaccine; Psychoneuroimmunology; Sickness behavior; Sleep; Social disconnection.
. 2025 Apr 14:S0889-1591(25)00147-3.
doi: 10.1016/j.bbi.2025.04.018. Online ahead of print. Effects of a mild inflammatory challenge on cytokines and sickness behavior: A randomized controlled trial using the influenza vaccine
Tatum A Jolink 1 , Mallory J Feldman 2 , Natalie M Antenucci 3 , Megan N Cardenas 3 , Taylor N West 3 , Zev M Nakamura 4 , Keely A Muscatell 5
Affiliations
- PMID: 40239903
- DOI: 10.1016/j.bbi.2025.04.018
The influenza vaccine has reliably been associated with mild, within-person increases in inflammation. However, the field lacks rigorous experimental work comparing the effects of the influenza vaccine to a placebo control on changes in plasma inflammatory cytokines and self-reported sickness behavior. In a double-blind, randomized, placebo-controlled trial, 102 participants received either the influenza vaccine or saline placebo. Four cytokines were measured in plasma 24-hours following injection; participants also reported on psychosocial outcomes, specifically sickness behavior, positive/negative affect, sleep, and subjective social disconnection. All cytokines-IL-6, IL-10, TNF-α, IFN-γ-were significantly increased in the influenza vaccine condition compared to placebo. None of the psychosocial outcomes differed by condition. This study fills a gap in the literature by presenting critical causal evidence that the influenza vaccine leads to elevated levels of four inflammatory cytokines, compared to placebo control. However, a more robust increase in inflammation or a larger sample size may be necessary to observe differences in self-reported sickness behavior and other psychosocial outcomes.
Keywords: Affect; Inflammation; Influenza vaccine; Psychoneuroimmunology; Sickness behavior; Sleep; Social disconnection.