This editorial lists the main current theories on long COVID, such as the theory of viral persistence and the one of immunothrombosis associated with deregulation of the immune system; it is discussed as well their interrelation, which finally explains the etiopathogenesis and physiopathology of this new syndrome that afflicts the survivors of COVID-19; it is also discussed the link between viral persistence with the formation of amyloid microthrombi based on the hypothesis that the spike protein causes amyloidogenesis, inducing organic chronic damage that will characterize long COVID.© 2023 Revista Médica del Instituto Mexicano del Seguro Social.