Redefining Normal: Cytokine Dysregulation in Long COVID and the Post-Pandemic Healthy Donors

The COVID-19 pandemic has caused over 7 million deaths, but its legacy extends beyond mortality. SARS-CoV-2 infection induces immune alterations that persist post-recovery, manifesting not only in long COVID (LC) but also in healthy individuals. Cytokines serve as critical orchestrators of these processes. The goal of this study is to investigate post-pandemic immune remodeling through cytokine assessment in both patients with LC and healthy donor, and to compare the post-pandemic population with pre-pandemic controls to find changes in the immune responses and cytokine profiles. A panel of 47 immune mediators (cytokines, chemokines, and growth factors) was measured with the MAGPIX multiplex analysis. LC was characterized by an increase in IL-7, IL-8, IL-17F, IL-18, EGF, FGF-2, PDGF-AA, sCD40L, and MCP-3 and a decrease in IL-4, IL-13, IL-22, IL-27, and FLT-3L. Comparing post-pandemic recovered individuals with pre-pandemic healthy cohort, we saw an upregulation of IL-13 and MCP-3 and a downregulation of MDC, M-CSF, IL-12, and IL-17F. While LC is characterized by persistent immune imbalance—particularly in cytokine networks—our data emphasize the critical need to study healthy donors in both pre- and post-pandemic eras when analyzing and interpreting these changes.