Longitudinal SARS-CoV-2 Seroconversion Course and Antibody Levels by Blood Groups in Convalescent Plasma Donors in Turkey.

Objective: The present study investigates the seroconversion time course of the IgG antibody against SARS-CoV-2 and ascertains whether its levels change according to the patient's ABO blood group.

Method: A total of 36,003-convalescent plasma (CP) donations of 12,315 Turkish Red Crescent CP donors were analyzed. The ABO blood group of the CP donors was determined by Gel Centrifugation; and IgG was measured using the Euroimmun anti-SARS-CoV-2 ELISA. The differences in the distributions of mean IgG ratios among the different ABO blood groups were analyzed with One-Way ANOVA and Independent Samples T-test.

Results: Among the CP donors, 98.4% were male. An antibody response to SARS-CoV-2 was noted-although in a few CP donors- on the 244th day, and a significant association between the ABO blood groups and the mean IgG ratios was noted (p: 0.001). The highest (mean±SD) antibody level was observed in the AB blood group (39.5±15.7), followed by the B (37.9±11.5) and the A blood groups (36.6±10.7), while the lowest value was recorded in the O blood group (34.4±11.5). Significant differences between all paired groups were noted in pairwise comparisons. The Rh (-) blood group (37.4±13.6) had a significantly higher antibody level than the Rh (+) blood group (36.3±11.2) (p: 0.005).

Conclusion: An antibody response to SARS-CoV-2 was noted in a CP donor on the 244th day. The average IgG ratios were higher in the CP donors with the AB blood group, but lower in the O blood group. These results may be considered a valuable indication of the effectiveness of CP therapy used for the treatment of COVID-19 patients with clinically relevant blood types.