IL17A and COVID-19: Next, we evaluated IL-17 level in saliva samples of these patients and found that, similar to the circulatory IL-17 level, its level was significantly elevated in saliva of severe COVID-19 cases (Fig 1C, mean 138.8 pg.ml-1 in severe vs 78.8 pg.ml-1 in mild/moderate COVID-19 cases; unadjusted P<0.001).