Prevalence and Clinical Disease Severity of Respiratory Coinfections During the Coronavirus Disease 2019 Pandemic

Respiratory tract infections represent a global health concern. More than 1 pathogenic organism in the respiratory tract has been widely recognized owing to the availability of molecular detection technologies. However, the association between the occurrence of multiple-pathogen infections and clinical disease severity remains unclear. Multiple infections fall into two broad categories: Coinfection occurs when a person is found to be infected by two or more micro-organisms, but which infection was established first cannot be clearly determined, while superinfection is an infection arising when one or more infections is already present. This review presents an overview of the prevalence and clinical disease severity of respiratory co-infections and superinfections and discusses possible mechanisms of the interactions between viral infections.