Hyper-inflammation, whereby the immune system goes into overdrive and destroys the organs, is how covid-19 tends to kill.
The search for suitable anti-inflammatory drugs for covid-19 has already turned up one, dexamethasone. It is a cheap steroid that dampens the immune system across the board. In contrast, tocilizumab and sarilumab are more targeted. They are both made of antibodies that block the effect of interleukin-6, a protein that stokes the immune response and has been prominent in patients with covid-19.
Source: Repurposing drugs – Another life-saving treatment is found for covid-19 | Science & technology | The Economist