["American Journal of Human Biology, Volume 38, Issue 6, June 2026. ", "\nABSTRACT\n\nObjectives\nBoth psychosocial stress and current infection can increase the likelihood of reactivation of latent Epstein–Barr virus (EBV). Pregnancy and infection with SARS‐CoV‐2 can be stressful and modulate immune function. However, it is unknown how SARS‐CoV‐2 infection and stress further interact among postpartum women to affect EBV antigen and antibody expression.\n\n\nMethods\nWe examined associations among COVID‐19 diagnosis, self‐reported stress, and EBV immunoglobulin G (IgG) in previously collected data from 45 breastfeeding US women (1–18 months postpartum) during the height of the COVID‐19 pandemic. Between June 2020 and March 2021, stress survey data and capillary dried blood HemaSpot samples were collected from 25 SARS‐CoV‐2 infected and 20 non‐infected participants at multiple time points over the course of 60 days. Samples (N = 104) were later assayed for EBV IgG. Statistical methods were pre‐registered, and relationships among SARS‐CoV‐2 infection, stress, and EBV IgG were analyzed via mixed‐effects regression models, adjusting for time postpartum and time elapsed since enrollment.\n\n\nResults\nThere was a statistically significant association between self‐reported stress and EBV IgG levels, with higher average stress associated with higher average EBV IgG. EBV IgG relative concentration did not vary independently with COVID‐19 positivity status or the number of COVID‐19 symptoms.\n\n\nConclusions\nResults suggest that EBV IgG relative concentrations were elevated across sample participants by stress, but not by the relatively mild cases of COVID‐19 the mothers experienced.\n\n"]