Background: Since the first reports of COVID-19 disease, it has become clear that acute respiratory distress syndrome was responsible for a significant number of deaths among infected patients. Several studies have linked increased levels of proinflammatory cytokines in serum to pulmonary inflammation and extensive lung damage.Among proinflammatory cytokines, Interleukin-6 is the key cytokine that contributes to an inflammatory storm. Several studies have found that elevated IL-6 levels are associated with the severity of COVID-19 symptoms and death.Tocilizumab is monoclonal antibody that antagonizes the effect of IL-6. Early cytokine storm treatment may have benefits on COVID-19 patients' survival.

Methods:The present study was conducted on 91 COVID-19 patients, admitted to intensive care unit and took tocilizumab.The IL-6 serum level data were collected from patients' files pre and post-tocilizumab administration. Regarding these data, we could determine the clinical outcome after treatment.

Results:We demonstrated that there was a decrease in IL-6 serum level within both mild and moderate severity grades by 16.3% and 38.4% respectively, while there was a significant increase in the patients who had severe grade by 162%. There was a significant decrease in IL-6 serum level within recovered group by 66.1% and a significant increase within the mortality group by 256% pre and post-injection with tocilizumab.

Conclusion: IL-6 serum level may be a major indicator but not the sole driver in the pathology of COVID-19. So, when we assess IL-6 serum level, we should take into consideration other cytokines, and the usage of combinations of many blockages for these cytokines may improve the outcome.