Severe respiratory infections are characterized by elevated inflammation and generation of reactive oxygen species (ROS) which may lead to a decrease in antioxidants such as vitamin C and a higher requirement for the vitamin.

Coronavirus disease 19 (COVID-19) is a viral disease caused by the new coronavirus SARS-CoV-2. Like other coronaviral infections, SARS-CoV-2 causes oxidative and ER stress triggering cellular response pathways, mainly PERK and IRE1 branches of the UPR.