LAUSR

COVID-19 disease exhibits a very wide spectrum of severity. This strongly suggests that host factors influence outcomes. While acquired co-morbidities-such as age, obesity, history of smoking—are very likely related to clinical severity, it is also likely that genetic factors will prove to be relevant to the host thromboinflammatory response. Recently, investigators from China reported that ABO type was strongly statistically associated not only with acquiring SARS-CoV-2 infection but also with survival following infection. Zhao et al [1] compared ABO distributions on 1,775 patients with SARS-CoV-2 infection in China with 3,694 ABO types from a background healthy population. Of note, their reference population was not a cohort of uninfected patients admitted to the same hospital, but rather was a background reference population of ‘normal individuals’ from Wuhan. (The details of that cohort were not reported.) They found that blood group O was less common among infected individuals (25.8%) compared with healthy population-based controls (33.8%) and that group A was more common among infected individuals (37.7%) compared with healthy population-based controls (32.2%), p < 0.001. They also reported that, among 206 COVID-19 patients who died, blood group O was significantly less common (25.2%) compared with their reference population (33.8%, p=0.014). Their data are shown in the Table. They did not compare the ABO distributions among those hospitalized with COVID-19 versus those hospitalized with non-COVID-19 associated conditions, nor among infected survivors versus infected fatal cases. This latter comparison would be the most informative way to understand if a particular ABO group was associated with mortality within a cohort of infected individuals. Re-analyzing their data in this way, we find no association between ABO type and death among individuals hospitalized with COVID-19 (X = 1.35, p=0.717). Similar findings from Wuhan were published by Li et al. [2]