IL6 and COVID-19: In all of the COVID-19 cohorts included in a recent meta-analysis, IL-6 levels were significantly elevated (approximately 3 fold) in patients with complicated disease compared to those with non-complicated disease.38 In the largest of the individual studies (n = 452), the median plasma concentration of IL-6 was 25.5 pg/ml,39 in line with levels observed in severe SARS-CoV40 and MERS-CoV infection.41