Study Identifies Distinct Immune Biomarkers of Long COVID in Blood

A study published April 14, 2026 identified specific soluble immune biomarkers — including IL-20, MCP-1, and NBL1 — that reliably distinguish Long COVID patients from those who fully recovered. Researchers described the findings as a major step toward clinical diagnostic tools and treatment targets for an estimated 65 million people globally living with Long COVID. The biomarker signature was consistent across age groups and COVID variant exposures, suggesting a common immunological mechanism underlying the condition.