Blood group O and post-COVID-19 syndrome

Abstract

ABSTRACTObjectiveThe ABO blood group system modulates the inflammatory response and has been involved in COVID-19. O-group protects against SARS-CoV-2 infection, but there are no data regarding post-COVID-19 syndrome (PCS). Our aim was to assess this possible association.Subjects and methodsCase-control study in a community setting, with subjects who had experienced mild COVID-19. Cases were PCS+, controls were PCS-, and the exposure variable, O-group. Epidemiological data (age, sex, BMI, smoking, comorbidities), laboratory parameters (inflammatory markers, IgG antibodies, blood type) and clinical data were collected. Composite inflammatory indices were developed. Multivariate analyses were performed.ResultsWe analyzed 121 subjects (56.2% women), mean age 45.7 ± 16 years. Blood group frequencies were 43.3%, 7.7%, 5.7%, and 43.3% for A, B, AB and O, respectively. Thirty-six patients were PCS+. There were no significant differences between cases and controls. Compared to non-O, a higher prevalence of PCS (p=0.036), number of symptoms (p=0.017) and myalgia (p=0.030) were noted in O-group. Concerning inflammatory markers, PCS+ and PCS-showed no differences in A, B, and AB groups. In contrast, O-group PCS+ patients had significantly higher lymphocyte count, higher levels of fibrinogen and CRP, and higher percentages of 3 composite indices, than PCS-subjects. The O-group showed a 4-fold increased risk of PCS compared to non-O (adjusted OR=4.20 [95%CI, 1.2-14]; p=0.023).ConclusionAn increased risk of PCS has shown to be associated with O-group, after controlling for confounders. In O-group subjects with PCS, slightly albeit significant, raised levels of fibrinogen, CRP, and lymphocyte count, have been demonstrated.