COVID19's cytokine storm ushers in a local complement storm in the lungs A new study published in the journal Science Immunology analyzed lung epithelial cells from patients infected with COVID-19 and found the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) induces the complement system as a dangerous weapon for viral infection. The complement system is an extension of the innate immune system to recognize pathogens and remove them. Prior research has shown a correlation between severe COVID-19 infection and high levels of complement. The mechanism of action is driving the JAK1/2-dependent local complement hyperactivation. Using the JAK1/2 inhibitor ruxolitinib alone or with remdesivir normalized interferon signature genes inhibited the C3a protein of the complement system created from infected lung cells.