SARS-CoV-2 seroprevalence and gender-related haematological features in asymptomatic blood donors

COVID-19 can either cause death or go unnoticed but antibodies will remain protecting us of SARS-CoV-2 reinfection for an uncertain time and to an uncertain extent. Our aim was to describe seroprevalence evolution from summer 2019 to autumn 2020 in Spain and to describe its relationship with age, blood group and haematological parameters.Sera and plasma from historical donation archives excluding convalescent were randomized and a total of 12,313 donations tested by a Chemiluminiscent analysis for anti SARS-CoV-2 N protein total immunoglobulins. Blood donors were 60.9% males, average age 46+/-13. Sex, age, blood group, blood cell counts and percentages and immunoglobulin concentrations were extracted from electronic recordings.A seroprevalence of 6.7% in blood donors was found by the end of the first wave. No differences by sex, age or blood group were found regarding antibodies. Leukocyte count (p=0.026), haematocrit (p<0.001) and haemoglobin (p<0.001) were lower in positive donations than in negative ones. Sex differences were present in neutrophils, leukocytes, haemoglobin and haematocrit as related to SARS-CoV-2 antibodies.Seroprevalence due to asymptomatic cases would resemble that of global population. Sex and age would not affect COVID-19 susceptibility but its severity. Gender differences related to COVID-19 in leukocytes, haemoglobin and haematocrit would be present in asymptomatic individuals. Further studies are needed to confirm these gender differences as they can help better understand the immune response to COVID-19, its pathogenesis and prognosis.