RESUMEN
BackgroundOne of the most questioned issues about SARS-CoV2 immunity is how long does it last. Whether lasting differences exist between infection and vaccination boosted immunity is yet to be known. The answer to this question will determine key issues such as the reliability of individual and herd immunity or the need of sanitary restrictions or periodical revaccination. The aim of this study was to determine how long total anti SARS-CoV2 antibodies due to past infection persist in peripheral blood and whether sex, age or haematological features can influence their lasting. Material and MethodsA total of 2432 donations SARS-CoV-2 from 662 repeat donors from April 2020 to February 2021 were analysed. Donors were 69.7% males and their average age was 46. An automated chemilumiscence immunoassay for total antibodies recognizing N protein of SARS-CoV-2 in human serum and plasma was performed. Results and discussionIn 97.6% donors with follow-up, anti SARS-CoV-2 protein N total antibodies remained positive up to 46 weeks after first positive determination. Blood group was not related to antibody waning. Lower lymphocyte counts and higher neutrophils and as well higher seric IgA would help predict future negativization of antibodies. The vast majority of donors keep their total immunoglobulins anti SARS-CoV-2 positive for longer than 10 months. Ageing might have a protective effect against antibody waning but, given the small number of cases that become negative, more studies, or larger cohorts would be needed to confirm these facts.
RESUMEN
Background and objectivesCOVID-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. Materials and methodsSera 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. ResultsA 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. ConclusionsSeroprevalence 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.