Avaliacao Dos Indicadores De Solicitacoes Transfusionais Para O Gerenciamento Da Rotina Laboratorial

Introducao/Objetivo: A analise automatizada da imuno-hematologia dos pacientes (tipagem sanguinea ABO e Pesquisa de anticorpos irregulares - PAI) e realizada rotineiramente em horarios pre-estabelecidos (amostras processadas em lotes a cada 1h30) em nosso servico. No entanto, para as solicitacoes transfusionais urgentes, as analises destas amostras devem ser priorizadas. Desta maneira, e realizada uma avaliacao medica de todas as solicitacoes de sangue e, dependendo da classificacao, os exames sao realizados imediatamente ou nos lotes de 1h30. O monitoramento desse processo garante a qualidade e a seguranca do servico, considerando que o aumento das solicitacoes urgentes impacta diretamente na rotina do laboratorio. Neste estudo, analisamos nossa experiencia de 5 anos de transfusao por meio de dois tipos de indicadores. Metodos: Todos os pedidos de transfusao de sangue sao pre-classificados pelo departamento medico de acordo com sua urgencia clinica, atraves do uso de marcadores coloridos. O marcador amarelo indica o pedido de transfusao principalmente para pacientes em cirurgia, que tenham amostras coletadas no prazo de 72 horas apos a transfusao e apresentem PAI negativo. O marcador azul indica a solicitacao para pacientes nao cadastrados anteriormente no banco de sangue ou sem resultado de PAI dentro de 72 hs. O percentual de cada marcador (amarelo ou azul) em relacao ao numero total de solicitacoes foi analisado mensalmente de 2017 a 2021 como indicadores. Os limites maximos aceitos foram de 2,0% e 5,0% para os indicadores amarelo e azul, respectivamente. Os resultados foram analisados utilizando-se o teste t e p < 0,05 foi considerado significativo. Resultados: O indicador amarelo mostrou uma reducao gradual no percentual de 2017 para 2021 (2,9% em 2017 para 0,7% em 2021) e, consequentemente, observou-se uma evolucao progressiva no percentual dos meses em que a meta foi atingida (2017: 0%, 2021: 100-%). Para o indicador azul, tambem foi observada uma reducao do percentual de solicitacoes (2017: 5,7% e 2021: 3,6%), porem, a meta somente foi atingida em todos os meses do ano de 2020. Foi observado que as diferencas estatisticas ocorreram entre 2017/2018 (Indicador amarelo p = 0,01, Indicador azul p = 0,03) e tambem entre 2019/2020 (Indicador amarelo p = 0,04, Indicador azul p = 0,01). Discussao: No primeiro periodo (2017/2018) a reducao foi atribuida ao treinamento medico/laboratorial para a classificacao adequada das solicitacoes e, no segundo periodo (2019/2020) alem de um rigido acompanhamento do indicador, houve tambem a reducao das cirurgias eletivas e emergenciais devido a situacao imposta pela pandemia COVID-19. Conclusao: Segundo os dados apresentados, houve uma reducao significativa das solicitacoes de transfusao urgente entre 2017 e 2021. Essa reducao somente foi possivel de ser alcancada atraves da avaliacao sistematica dos indicadores. Assim, o uso desta ferramenta e de extrema importancia para garantir a gestao da rotina laboratorial, especialmente em situacoes urgentes, nas quais contribui diretamente para a seguranca do processo. Copyright © 2022

Dois Pacientes Com Sindrome De Guillian-Barre Apos Infeccao Por Sars-Cov-2

Objetivos: Descricao de dois casos de Sindrome de Guillain-Barre (SGB) possivelmente relacionados ao SARS-CoV-2. Materiais e metodos: Avaliacao dos achados clinicos e laboratoriais em pacientes que evoluiram com a SGB apos a infeccao por SARS-CoV-2. Resultados: 1degree. Homem de 56 anos, com lupus eritematoso sistemico e insuficiencia renal cronica, apresentou PCR nasofaringeo positivo para Covid-19, em 7 de setembro de 2021. Evoluiu com insuficiencia respiratoria 10 dias apos a admissao no hospital, porem com evolucao progressive, comprometimento neurologico, com parestesia dos pes/maos e abolicao dos reflexos tendinosos. O liquido cefalorraquidiano deste paciente demonstrou dissociacao albumino-citologica e o padrao eletrofisiologico foi compativel com doenca desmielinizante. O paciente nao apresentou melhora apos tratamento com esteroides e imunoglobulina intravenosa, e vinte dias apos seus primeiros sintomas neurologicos, iniciamos o tratamento com 5 plasmaferese terapetica (PFT), 1 procedimento/dia, com troca de uma volemia plasmatica. Apos 3 sessoes de PFT, houve melhora clinica significativa, inclusive no exame neurologico do paciente. 2degree. Mulher de 22 anos, previamente higida, apresentou infeccao respiratoria superior e PCR nasofaringeo positivo para Covid-19, em 10 de janeiro de 2022. Apos 3 dias do diagnostico, esta paciente apresentou parestesia ascendente progressiva simetrica. A avaliacao eletrofisiologica comprovou uma polineuropatia desmielinizante segmentar e o exame do liquido cefalorraquidiano mostrou dissociacao albumin-citologica. O tratamento com pulsoterapia com corticoides e imunoglobulina endovenosa nao mostrou resultado satisfatorio nesta paciente, que evoluiu com caracteristicas autonomicas e insuficiencia respiratoria aguda. Portanto, foi necessario iniciarmos o protocolo institucional de PFT, 1x/dia, com troca de uma volemia plasmatica. Apos a quarta PFT, o exame clinico neurologico da paciente apresentou melhora significativa, podendo inclusive ser extubada. Finalizamos o tratamento com mais quatro PFTs adicionais ate alta hopsitalar da mesma para reabilitacao. Conclusao: A SGB e uma doenca paralitica flacida aguda com fraqueza progressiva simetrica e arreflexia, geralmente ocorre apos uma infeccao respiratoria ou gastrointestinal, com apresentacao variando entre 3 e 50 dias. O suposto mecanismo fisiopatologico e uma resposta autoimune aberrante que evoca uma reacao cruzada contra os antigenos dos nervos perifericos. Nesses dois casos acima, as caracteristicas epidemiologicas, clinicas e os achados laboratoriais sugerem que a infeccao por SARS-CoV-2 pode ser mais uma infeccao viral causadora de GBS. A resposta ao tratamento com TPE em ambos os pacientes foi positiva e gratificante. Copyright © 2022

Assessment of Key Performance Indicator as a Quality Tool for Management of Urgent Transfusion Requests

Background/Case Studies: Automated analysis of patients' immunohematology (ABO blood typing and Irregular Antibody Screening-IAS) is routinely performed at pre-established times (samples processed in batches every 1 h 30) in our service. However for urgent requests, it is necessary a faster approach. Therefore, a medical classification of all blood requests is performed and depending on these classifications the tests are performed immediately or in the 1 h 30 batches. Monitoring these processes ensures the quality and safety of the service considering that an increase in urgent requests directly impact the lab routine. In this study, we analyzed our 5-year experience transfusion urgencies through two kinds of KPI (Key Performance Indicator). Study Design/Methods: All Blood Transfusion requests are pre-classified by medical department according to its clinical urgency using colored tags. The yellow tag indicates transfusion requests mainly for surgery patients, who have samples collected within 72 h of the transfusion and presented a negative IAS. The blue tag indicates request for patients not previously registered in the blood bank or without IAS within 72 h. The % of each tag (yellow or blue) in relation to the total number of requests was analyzed monthly from 2017 to 2021 as a KPI. The maximum % accepted were 2.0% and 5.0% for yellow and blue KPI, respectively. The results were analyzed using the t test and p < 0.05 was considered significant. Results/Findings: The yellow KPI showed a gradual reduction from 2017 to 2021, and consequently an evolution was observed in the % of months in which the target was reached (see table below). For the blue KPI, a reduction was also observed, however, the goal was only reached in all the months of 2020. It was observed that statistic differences occurred between 2017/2018 (yellow KPI p = 0.01, blue KPI p = 0.03) and also for 2019/2020 (yellow KPI p = 0.04, blue KPI p = 0.01). In the first period (2017/2018) the reduction was attributed to medical/laboratory training to properly classifying the requests and, in the second period (2019/2020) besides a rigid follow up of the KPI, there was also a reduction in elective and emergency surgeries due to the situation imposed by the COVID-19 pandemic. Conclusion(s): According to the data shown, there was a significant reduction in urgent transfusion requests between 2017 and 2021. These decreases were only possible to be achieved through the systematic evaluation of the KPI. Thus, the use of this tool is extremely important to ensure the better management of the laboratory routine, especially in urgent situations, in which it directly contributes to ensuring the process safety.

Effect of SARS-CoV-2 pandemic in the routine of a hospital-based blood bank

Background: Since the beginning of SARS-CoV-2 pandemic, several restrictions on mass gatherings were necessary to be implemented due to the pan-lockdown, so the blood supply chain was considerably affected. Many issues were raised concerning maintaining an adequate and safe blood supply according to the demand and with minimum discard percentage. Aims: The study investigated the impact of the pandemic in blood donation and transfusion process and also the discard rate. Methods: We studied a period before (May 2018-February 2020) and after the beginning of lockdown (March 2020-December 2021), where several strategies had to be implemented in our hospital, like physical distancing measures, postponement of elective surgeries and priority in urgency medical and surgery admissions. In relation to the blood bank, our goal was to maintain a buffer stock of blood to a 2-week level, collecting blood donations only at the blood center and cancelling mobile blood donations. The blood donor recruitment was basically performed by phone, e-mail, WhatsApp and blood donations were scheduled in such a way to prevent any risk of people's agglomeration. The following collection data were analysed: number of blood donations, rates of repeated blood donors and mobile blood donations, number of red blood cells (RBC), plasma, platelets (random donor platelet-RDP and apheresis) and cryoprecipitate transfusions, discard rates by expiration or due to reactive serological screening. Results: Surprisingly, we noticed a 14% increase in blood donations after the beginning of lockdown (12,977 donations before pandemic and 14,793 after), with an important decrease for mobile blood donations (from 29.6% to 14.3%;p < 0.05). However, in the period before pandemic, there were 84.1% repeated blood donor whereas after the beginning of pandemic it declined to 82% (p < 0.05). No changes were observed in the percentages of reactive serological screenings in both periods: 1.32% and 1.42%, respectively (p = 0.47). As for discard due to expiration, we observed a decrease for both apheresis and RDP with 3.75% ± 1.62% for apheresis before and after pandemic, respectively (p < 0.05), 0.78% ± 0.17% for RDP before and after pandemic (p = 0.001). For RBC, there were no statistical difference in both periods;306/10,972 (2.78%) ± 378/12,563 (3.00%) units (p = 0.31). The transfusional demand in the studied periods demonstrated an increase from 18,672 to 22,007 (17.86%) transfusions, especially because of an increase for plasma transfusions requests: from 1727 to 2907 units (p < 0.05) due to patients undergoing therapeutic plasma exchange (1804 or 62% of units), Covid-19 convalescent plasma (381 or 13.1%), and 722 (24.8%) units, due to other causes. We also had a significantly increasing demand for platelets (from 5420 to 6091;p < 0.05) and for RBC (from 11,047 to 12,567, p < 0.05) units, and a drop for cryoprecipitate (from 478 to 442;p < 0.05) doses. Summary/Conclusions: Besides all global restrictive measures adopted related to Covid-19 pandemic, we could maintain our inventory well enough to attend our transfusional demand, including when an increase was required, since we were a reference center for severe Covid-19 cases. Finally, in times of pandemic, it is crucial to maintain a buffer stock of blood besides a pro-active management through a strict surveillance between the recruitment team and coordinator staff, according to daily transfusional demand.

Could autoimmune hemolytic anaemia be triggered by SARS-COV- 2 vaccine?-case report

Background: Autoimmnue hemolytic anaemia (AIHA) is characterized by the production of autoantibodies against red cells antigens, leading to hemolysis. AIHA can be primary or secondary to rheumatologic and lymphoproliferative diseases, infections, drugs and vaccines. Several immune phenomena were reported after massive SARS-CoV-2 vaccination, including myocarditis, neurological syndormes, immune thrombocytopenia, among others. Aims: We hereby describe an AIHA case possibly related to SARSCoV- 2 vaccination. Methods: Assessment of the clinical evaluation along with the laboratory and immunohematological tests in a symptomatic patient fwe days after receiving the vaccine. Results: A 72-year-old womwn, previously healthy, rceived her first dose of Coronavac (Sinovac, inactivated virus), in January 2021. After 7 days, she was admitted with fatigue and myalgia. Laboratory results revealed haemoglobin 4.9 g/dl, reticulocyte count 31.7%, total bilirubin 9.15 mg/dl, indirect bilirubin 7.88 mg/dl, haptoglobin<6 mg/dl and lactate dehydrogenase 953 U/L. The peripheral blood smear showed spherocytes and polychromasia. The nasopharyngeal PCR test for Covid-19 was negative. Regarding the immunohematological tests, the patient was group O R1K-k+, polyspecific direct antiglobulin test (DAT) was reactive for IgG and C3d, but the monospecific DAT showed only IgG. The eluate was reactive against all test cells. After all adsorptions performed, no alloantibody was detected and the eluate confirmed only the presence of an autoantibody, with no specificity. The patient was successfully managed with steroids, cyclophosphamide and transfusion support (OR1r, K-, antigens S and JKa negative, according with genotyping). No other causes of AIHA were found in the patient's screening and the patient did not have covid prior to vaccination. Summary/Conclusions: In this case, the temporal relationship between the vaccination and the symptoms of AIHA suggests a possible and rare haematological side effect of the vaccine which are able to activate both cellular and humoral immune systems with an important role in the interactions between dendritic cells, B and T cells, and the self-tolerance system. Since there is the increase of the global number of vaccinated people and few of this reports of this phenomenon have described in the literature, we considered it important to disclose this case in our service.

UTILIZAÇÃO DO PLASMA FRESCO CONVALESCENTE EM PACIENTES DE ALTO RISCO DURANTE FASES PRECOCES DE INFECÇÃO POR COVID-19

Objetivos: Dentre o arsenal terapêutico atual contra a COVID-19, a terapia com plasma convalescente proveniente de doadores recuperados da COVID-19 (CCP), pode ser benéfica em pacientes de alto risco que estejam em fase precoce desta infecção, especialmente até o quinto dia de sintomas. Relatamos abaixo dados iniciais de uma série de pacientes de alto risco com infecção por SARS-CoV-2 que receberam esta terapêutica. Material e métodos: As unidades de CCP foram coletadas por aférese e submetidas à titulação de anticorpos neutralizantes através da neutralização viral em placa. As unidades com títulos ≥ 160 foram liberadas para uso, constituídos pools de duas doações e submetidas ao tratamento de redução de patógenos pelo Intercept®. Os critérios de inclusão dos pacientes para o estudo foram: idade ≥ 60 anos, presença de comorbidades, diagnóstico confirmado de SARS-CoV-2 por RT-PCR e sintomas de COVID-19 com início ≤ 5 dias. Após solicitação médica e assinatura do termo de consentimento informado, os pacientes receberam pré-medicação (anti-histamínico) seguido de uma dose única de plasma convalescente (200 mL). O desfecho primário foi considerado óbito após 28 dias da transfusão e o secundário, internação após receber a transfusão ambulatorial. Resultados: Estudamos 120 pacientes entre 01/01/2021 e 31/07/2021, sendo 37 (30,8%) pacientes internados devido à condição clínica no momento da transfusão e 83 (69,2%) ambulatoriais;84 (70%) eram masculinos e 36 (30%) femininos. A média de idade foi de 66 anos. Quanto aos antecedentes vacinais: 40/120 (33,4%) haviam recebido pelo menos a primeira dose da vacina (período médio da vacina à transfusão de plasma de 46 dias) sendo 25/40 (62,5%) Coronavac, 14/40 (35%) Astrazeneca e 1/40 (0,5%) Pfizer. As comorbidades mais encontradas foram hipertensão arterial (57,5%), obesidade (36,7%), diabetes (28,4%), cardiopatia (25%), neoplasia (18,4%), imunodeficiência (13,4%) e pneumopatia (8,4%). Observamos 3 (2,5%) reações transfusionais leves (2 alérgicas, 1 RFNH), sem danos aos pacientes. Entre os pacientes internados, 5/37 (13,5%) foram a óbito, pela própria condição clínica de base, associada às comorbidades, principalmente imunossupressão. Tais óbitos ocorreram em média, 25 dias após a transfusão. Dos pacientes ambulatoriais, 14/83 (16,9%) internaram nos 28 dias seguintes à transfusão, permanecendo, em média, 15 dias no hospital. Neste grupo, houve apenas 1 (1,2%) óbito, por complicações hemorrágicas e cardiológicas, em paciente com importante imunossupressão por transplante hepático recente. Discussão: Nossos dados demonstram a viabilidade do tratamento precoce na infecção pelo SARS-CoV-2 utilizando-se plasma convalescente com altos títulos de anticorpos neutralizantes em pacientes de alto risco, internados ou não, prevenindo, inclusive, internações subsequentes.

Development of a Robust Mathematical Model to Estimate COVID-19 Cases in Lebanon Based on SEIRDV Modified Model

COVID-19 pandemic triggered a global crisis, whether it comes to a huge global health emergency or to the global economic crisis situation. It is one of the greatest challenges this generation is facing. Computational simulations are playing a huge rule in the prediction of the current pandemic. Such simulations enable early predictions for future projections of the pandemic and are useful to estimate the efficiency of control action taken against this virus. The SEIR (Susceptible-Exposed-Infectious-Recovered) model is a commonly used model to compute the simulations of any infectious viral diseases and was widely used before to model and simulate SARS, EBOLA, Spanish Flu, etc. This paper presents a modified SEIR model with additional parameters taken into consideration such as the death, recovered and recovered with the chance of being infected again, vaccination and control efficiency;where the control represents the effectiveness of the lockdown. This factor is being controlled in order to extend the projections into controlled death, recovery, and infection. Specific information including time delay on the development of the pandemic due to control action measures, ageing factor of the population, and resusceptibility with temporal immune response are also included in the model. After that, the model examines the outcome of the system after adding a controllable vaccine with taking into consideration the vaccination rate and vaccine's efficacy. The numerical results are demonstrated to show the predictability range of this model.

Screening for SARS-CoV-2 antibodies in convalescent plasma (CCP) in Brazil: Results from a voluntary convalescent donor program

Background/Case Studies: We describe the COVID- 19 Convalescent Plasma (CCP) program from two Brazilian hospitals for treatment of severe/critical patients Study Design/Methods: Mild/moderate COVID-19 convalescents were selected as CCP donors after RT-PCR confirmed SARS-CoV-2 infection and absence of symptoms for ≥14 days plus: 1) age (18-60yrs), body weight >55kg;2) immunohematological studies;3) no infectious markers of HBV, HCV, HIV, HTLV1-2, Chagas and syphilis infection;4) no HLA antibodies (multiparous);5) Second RT-PCR (nasopharyngeal swab and/or blood) negativity;6) virus neutralization test (CPE-based VNT nAb) and anti-nucleocapsid (NP) SARS-CoV-2 IgM, IgG and IgA ELISAs. Results/Findings: Among 271 donors (41 females, 230 males), 250 presented with nAb. Final RT-PCR was negative on swab (77.0%) or blood (88.4%;p= 0.46). Final definition of RT-PCR was only defined at>28days after full recovery in 59/174 (33.9%) RT-PCR-ve, and 25/69 RT-PCR+ve (36.2%;13 between 35-48 days). NAb titers ≥160 was found in 63.6%. Correlation between IgG signal/ cut-off ≥5.0 and nAb ≥160 was 82.4%. Combination of final RT-PCR-ve with nAb ≥160 was 41.3% (112/271). Serial plasma collection showed decline in nAb titers and IgA levels (p<0.05), probably denoting a “golden period” for CCP collection (≤ 28 days after joining the program);IgA might have an important role as nAb. Donor's weight, days between disease onset and serial plasma collection, IgG and IgM levels are important predictors for nAb titer. Conclusions: RT-PCR+ve cases are still detected in 36.2% within 28-48 days after recovery. High anti-NP IgG levels may be used as surrogate marker to nAb.

Kinetics of neutralizing antibodies (nAb) SARS-CoV-2 and anti-nucleocapsid (NP) antibodies in convalescent plasma donors

Background/Case Studies: COVID-19 convalescent plasma (CCP) has been used for therapy in severely affected COVID-19 patients. The rational relies on the presence of nAb in convalescent's bloodstream, which might suppress patient's viremia. Little is known about the nAb kinetics in CCP donors. Study Design/Methods: A cohort of previously RTPCR+ ve, male, volunteer, non-remunerated, mild convalescent donors has been studied, based on serial virus neutralization tests (CPE-based VNT, GenBank: MT MT350282, transformed in natural log) and specific IgM, IgG and IgA anti-nucleocapsid protein (NP) SARS-CoV-2 ELISA, depicted as signal/cutoff (S/CO). Results/Findings: A total of 63 donors were evaluated within a period ranging from 14-97 days after full recovery of symptoms (DARS). There was initially a decline in nAb and IgA anti-NP from the first to third collection (median = 45days), followed by an unexpected rise in two additional collections. No differences were seen for IgM and IgG anti-NP. Data are shown below, with statistical values between subsequent samples. Conclusions: There is a great variability in nAb titers, with a declining trend over time. Although this was clear during the first three collections, the sudden rise could be explained by biological nAb fluctuation or by viral re-exposure after recovery, due to contact with infected people (pandemic still active in our region). Although IgA anti-NP shows a wide range, its declining trend could be signaling a possible role of IgA as an important component of nAb. Further studies are required to better understand the kinetic behavior of these antibodies.

Preservation of SARS-CoV-2 neutralizing antibodies (nAb) or anti-nucleocapsid proteins (NP) in convalescent donor plasma (CCP) Treated with Amotosalen/UVA Illumination (A/UVA)

Background/Case Studies: COVID-19 Convalescent plasma (CCP) has been used for therapy in severely symptomatic COVID-19 patients. Pathogen reduction (PR) has been proposed to mitigate the risk of transfusion-transmitted infectious agents. We investigate the impact of A/UVA on nAbs and anti-NP (IgM, IgG and IgA) PR treatment of CCP units. Study Design/Methods: Plasmapheresis CCP units (600 mL) were collected from a cohort of previously confirmed male RT-PCR positive [+ve] COVID-19 mild/ moderate convalescent patients, all first-time and nonremunerated volunteers, with >14 days after full recovery of symptoms. CCP units were treated with INTERCEPT Blood System (Cerus Corporation, Concord, USA) according to manufacturer's instructions, either individually or pooled two by two. After treatment, units were separated into 200 mL doses. Pre- and post-PR treatment samples were harvested and kept at 4oC for 3-5 days prior to testing for nAb titers using a CPE-based virus neutralization assay (GenBank: MT MT350282), and specific IgM, IgG and IgA anti-NP antibodies by ELISA. Results/Findings: A total of 16 individual and 94 pooled units were treated (n =110 CCP donations), rendering 330 x 200 mL treated CCP therapeutic doses. There were no statistical differences in samples harvested before versus after A/UVA treatment (all p>0.05, Wilcoxon test) for nAb titers or IgM, IgG and IgA anti-NP absorbance levels, as shown in the table. Conclusions: Anti-NP IgM, IgG, IgA, and nAbs are not adversely impacted by A/UVA treatment, suggesting this PR technology can be employed to mitigate the risk of transfusion-transmitted infections after collection of CCP donors, who are often first time blood donors. With most CCP units destined to treat older, immunosuppressed patients with several comorbidities, the use of A/UVA PR treatment is not only safe and recommended, while preserving anti-SARSCoV- 2 antibodies in CCP units.

Anti-A and SARS-CoV-2: An intriguing association

Background/Case Studies: It is not clear which individual characteristics can determine susceptibility and intensity of symptoms, however, age, sex, ethnicity, hypertension and some haematological biomarkers, as Ddimer, thrombocytopenia and lymphopenia were associated with a worse outcome. Recently, it has been hypothesized that ABO blood groups can be related to susceptibility to the SARS-CoV-2 infection. Considering that the first studies reported A group as a risk factor and O group as a protection, some authors have been suggesting that the anti-A antibodies, and not the blood group, could be responsible for the findings. Study Design/Methods: A retrospective study with 430 COVID-19 individuals (268 COVID-19 convalescent plasma donors-CCPD and 162 COVID-19 inpatients-CIP) from two Brazilian reference hospitals, confirmed by RTPCR, and 2,212 healthy volunteer blood donors (VBD) as control group, that were evaluated and divided into two groups: one with anti-A (O/B blood groups) and one without anti-A group (A/AB blood groups). Immunoglobulins and neutralizing antibody titres were measured for CCPD and CIP. Multivariate logistic regression and nonparametric tests were performed. Results/Findings: Although O blood group was the most frequent ABO group among VBD, A blood group was more frequent among COVID-19 individuals (CCPD 47.8%, CIP 43.2%, VBD 35.5%, p<0.001). There was no statistical difference in blood groups distribution between CCPD and CIP (p=0.268). In our cohort, for each increased age year there was 6% more chance for COVID-19 (OR: 1.06;CI 95%: 1.05-1.06, p<0.001), males showed 27% more chance for the disease (OR: 1.27;CI 95%:1.02-1.59, p=0.035) and O/B blood groups showed 38% less infection prevalence (OR: 0.62;CI 95%: 0.5-0.7, p<0.001). Considering the fact that higher anti-A is usually described in the O blood group, data from O versus B blood groups individuals were analysed and the former showed 34% less chance for COVID-19 (OR: 0.66;CI 95%:0.46-0.95, p=0.026). There was no difference regarding ABO group found when COVID-19 inpatients of all blood types were analysed. Immunoglobulins A, M and G (IgA, IgM and IgG) and neutralizing antibodies (NAbs) for SARS-CoV-2 were lower in COVID-19 individuals O/B blood groups (NAbs p=0.008, IgM p=0.03, IgG p=0.02, IgA p=0.03). Conclusions: In our retrospective cohort, the COVID-19 individuals O/B blood groups (which produces anti-A) had 38% less chance to have a diagnosis of COVID-19 (p<0.001) and the same groups showed lower titers of neutralizing antibodies, IgM, IgG and IgA. Groups O/B showed a protective factor against the SARS-CoV-2 infection, but it was not associated to COVID-19 inpatients (versus COVID-19 convalescent plasma donors) suggesting that blood type is not associated to SARSCoV- 2 infection severity.