Abstract
Coronavirus disease 2019 (COVID-19), a respiratory illness caused by infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has claimed over one million lives worldwide since December 2019. The complement system, while a first-line immune defense against invading pathogens, has off-target effects that lead to increases in inflammation, tissue damage, and thrombosis; these are common, life-threatening complications seen in patients with COVID-19. This review explores the potential impact of complement activation in COVID-19 and possible treatments targeting the complement system.