The immune system is usually seen as our ally in fighting disease, but in the case of coronavirus, it can sometimes turn into our foe. A phenomenon known as a cytokine storm has been implicated in many fatal cases of Covid-19, and several drugs are currently being tested to calm this storm and raise patients’ chances of survival. These drugs are known as anti-C5 drugs as they prevent a molecule named C5 from triggering the complement system to produce cytokines, which are known to cause inflammation in the body. Over-activation of cytokines (also known as a cytokine storm) has also...