Covid-19 showed inconsistent results.Tocilizumab has been used by doctors since the start of the pandemic with the hope of tamping down an abnormal immune response known as a "cytokine storm" that causes severe organ damage in some hospitalized Covid-19 patients.Unlike steroids, which suppress the immune system more broadly, tocilizumab blocks a particular signaling protein from triggering inflammation.Of the three new studies, the largest was led by the Harvard-affiliated Brigham and Women's Hospital in the United States on more than 4,000 critically ill Covid-19 patients.The risk of death at 30 days was 28 and 38 percent among tocilizumab-treated and non-tocilizumab-treated patients, respectively.But the American study was.