IL18 and COVID-19: In addition, patients with higher IL-18 levels exhibited an increased risk of hospitalization burden after COVID-19 infection supporting similar observations about IL-18 in prior unadjusted studies.5,50 Notably, Rodrigues et al. found no significant difference in IL-18 levels between patients with severe versus mild/moderate COVID-19,4 highlighting the importance of IL-18 as a possible biomarker for late stages of COVID-19 rather than milder, early cases.