Abstract
Since the SARS CoV-2 virus was first identified in December 2019, huge scientific endeavor has occurred in order to characterize the pathogenesis of this virus and how best to treat it. Early observations noted marked cytokine release, coagulopathy and a prothrombotic phenotype associated with severe disease. The potential contribution of red blood cells to these findings remains an area of ongoing investigation.
While there is no evidence of direct infection of red blood cells by the SARS CoV-2 RNA virus, anaemia and increased variability in shape and size of red cells have been shown to be associated with adverse outcomes in COVID-19 infection. This is likely related to the impact of inflammatory cytokine-induced oxidative stress on erythrocytes, where decreased levels of reducing agents have been shown to correlate with disease severity. The consequences of increased oxidative stress on red cells include membrane damage leading to the morphological abnormalities seen in patients, and increased rates of programmed red cell death with resultant anaemia. Production of nitric oxide by red cells is altered, possibly as a means to alleviate tissue hypoxia in these patients, and red cells may also demonstrate enhanced lactate influx, possibly reducing circulating levels at a time of increased glycolysis.
In this review we discuss the currently available evidence describing the impact of SARS CoV-2 infection on erythrocytes and the possible roles they play in patients with COVID-19 infection.