IL6 and post-traumatic stress disorder: In particular, among the signs and symptoms attributable to long COVID, high serum IL-6 levels were associated with a higher incidence of mobility decline (OR = 2.55; 95% CI: 1.08–9.40; p = 0.02) and PTSD (OR = 2.38; 95% CI: 1.06–8.61; p = 0.02) (Figure 1; Table S1).