More on ‘Association between ABO blood groups and risk of SARS-CoV-2 pneumonia’

We read with interest the recent report from Li et al.1 describing an association between ABO blood groups and risk of SARS‐CoV‐2 pneumonia. In an initial study of 265 patients with COVID, the authors observed that blood group O individuals were significantly underrepresented amongst patients who required hospitalization for severe COVID‐19 infection (P < 0·01). Conversely, blood group A was significantly more common in patients with severe COVID‐19 compared to the local population (P = 0·017). Subsequently, in a larger validation cohort that included 2 153 patients with COVID‐19, this ABO effect was reproduced with blood group O again being associated with a significant protective effect (P < 0·001). In keeping with these data, another independent study (n = 2 173) also reported that blood group O was associated with reduced susceptibility to severe COVID‐19.2 Since the pathogenesis underlying COVID‐19 remains poorly understood, we believe that these novel findings provide interesting insights into biological mechanisms that may contribute to interindividual differences in COVID‐19 susceptibility.