Plasma from Puumala orthohantavirus-infected HFRS patients (n=28) were analyzed for IL-6 trans-signaling potential and its associations to severity.<h4>Findings</h4>In vitro, sIL-6R treatment of infected cells enhanced IL-6 and CCL2 secretion, upregulated ICAM-1, and affected VE-cadherin leading to a disrupted cell barrier integrity. The gene discussed is IL6R; the disease is hemorrhagic fever with renal syndrome.