BackgroundSeroprevalence analysis of SARS-CoV-2 is one of the keys to accurately monitor pandemics and help the authorities make health decisions and adjust the current social interventions. The aim of this study was to determine retrospective seroprevalence evolution among blood donors along prepandemic months, and the first wave in Spain. A secondary objective was to determine whether age, blood group or haematological parameters are related to recent past infection.Material and MethodsA total of 12719 donations SARS-CoV-2 from July 2019 to October 2020 were analysed. Donors were 60.9% males and their average age was 46+/-13. An automated chemiluminiscence double-antigen sandwich immunoassay for the in vitro semi quantitative detection of total antibodies to SARS-CoV-2 in human serum and plasma was performed.ResultsSeropositivity donation rate grew up from week 11 to week 21, reaching plateau by near 8% donations, sustained until week 43 when 2nd wave arose in our country. 6.7% individuals were positive by the end of 1st wave. No differences by sex age or blood group were found regarding antibodies. Lymphocyte were significantly higher in positive woman as compared to negative ones and haemoglobin were lower in positive men as compared to negative ones.DiscussionSeroprevalence due to asymptomatic cases would be equivalent to that of general population. Sex and age would not affect COVID-19 susceptibility but its severity. Gender differences are present even in asymptomatic individuals: females are possibly protected by their relative lymphocytosis and neutropenia whereas males are would be weaker as seropositive men show a decrease of haematocrit and haemoglobin. Further studies are needed to confirm these gender differences not only in severe but as well in asymptomatic cases as they can help better understand COVID19 pathogenesis and prognosis.

Background The vast majority of COVID-19 cases both symptomatic and asymptomatic develop immunity after COVID-19 contagion. Whether lasting differences exist between infection and vaccination boosted immunity is yet to be known. 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 methods A series of 2421 donations either of SARS-CoV-2 convalescent plasma or whole blood from 1107 repeat donors from January 2020 to March 2021 was analysed. An automated chemiluminescence immunoassay for total antibodies recognizing the nucleocapsid protein of SARS-CoV-2 in human serum and plasma was performed. Sex, age, blood group, blood cell counts and percentages and immunoglobulin concentrations were extracted from electronic recordings. Blood donation is allowed after a minimum of one-month post symptom’s relapse. Donors were 69.7% males and their average age was 46. The 250 donors who had later donations after a positive one underwent further analysis. Both qualitative (positivity) and quantitative (rise or decline of optical density regarding consecutive donations) outcomes were evaluated. Results and discussion In 97.6% of donors with follow-up, anti-SARS-CoV-2 protein N total antibodies remained positive at the end of a follow-up period of 12.4 weeks median time (1–46, SD = 9.65) after the first positive determination. The blood group was not related to antibody waning. Lower lymphocyte counts and higher neutrophils would help predict future waning or decay of antibodies. Most recovered donors maintain their total anti-SARS-CoV-2 N protein antibodies for at least 16 weeks (at least one month must have been awaited from infection resolution to blood donation). The 10 individuals that could be followed up longer than 40 weeks (approximately 44 weeks after symptom’s relapse) were all still positive.

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.

Antigen challenge involving exposure to straw and mouldy hay for 7 h produced lung function changes and neutrophil recruitment to the lungs in horses with chronic obstructive pulmonary disease (COPD). During the challenge, an increase in radiolabelled neutrophils in the lungs occurred, together with increased respiratory rate and pleural pressure. The role of platelet activating factor (PAF) in antigen-induced neutrophil accumulation, and increased pleural pressure and respiratory rate was investigated by administering the PAF receptor antagonist WEB 2086 to asymptomatic COPD horses prior to antigen challenge. WEB 2086 (3 mg/kg i.v.) did not affect antigen-induced changes in either neutrophil accumulation or respiratory function. These results suggest that PAF may not be an important mediator of the response to antigen in equine COPD.