Introduction: Investigators in China and the US have described an association between odd of Sars-CoV-2 infection and ABO blood groups, results converging to a higher rate of infection among type A and lower in type O subjects. These data were reinforced by an elegant study that employed a genome-wide association approach, and identified a region on chromosome 9 with frequency misbalance between severe Covid-19 patients and healthy blood donors, corresponding to the ABO locus. Authors went further in showing that the SNPs leading to the A blood group phenotype were more frequent in patients while the O blood group was rarer, the opposite seen among blood donors, both cohorts from Italy and Spain. Objective: To evaluate the frequency of ABO blood groups among patients submitted to Covid-19 testing at Dasa laboratories. Methods: Up to June 22nd 2020, 196,897 and 256,471 qPCR and serological tests respectively were performed at Dasa. Patients tested in parallel for ABO blood groups were identified (n = 6,457). qPCR – Samples were collected by nasopharynx and oropharynx swabbing and further transported in 3 mL saline. RNA was extracted on the QIASYmphony automated platform and 5 μL of eluate was directly added to a RT-PCR mixture containing primers and probe targeting the viral envelope gene in addition to RNAseP as a cellular control. Serology – Blood was drawn and transported to Dasa central lab where the following commercial kits were used: Euroimmun IgA/IgG EIA or Maglumi IgG/IgM CLIA. ABO typing – Phenotyping was performed by hemagglutination on the Wadiana automated system. Statistical analysis – The Chi-square test was used to estimate if the proportion of individuals infected differed significantly between blood group types. Results: Among all patients submitted to Sars-CoV-2 testing, we identified 6,457 that had a concomitant ABO blood group typing result, being 4,353 tested by qPCR and 2,275 tested for COVID-19 antibodies, while 171 did both. We also retrieved historical ABO blood group typing data from our records, representing 1,813,237 patients. Approximately 30% of all patients have one or more laboratory markers indicating previous or current SARS-CoV-2 infection, irrespective of the blood group. Additional analysis was performed restricting to A and O blood group types, as these were previously implicated in susceptibility and protection to SARS-CoV-2 infection. There was not a statistically significant difference between these groups, as well as for the other blood groups. Discussion Though we did observe a small trend for a higher frequency of type A subjects and a lower of type O among confirmed SARS-CoV-2 infected patients, our data failed to reproduce the skewed frequency of ABO blood group types reported on the Chinese and American populations. The strength of our work is the large number of COVID-19 suspects evaluated. We have limited access to clinical records so we didn‘t attempt to correlate ABO blood groups and disease severity. Further studies are necessary to elucidate whether blood groups indeed modulate the susceptibility to SARS-CoV-2 infection and, if proven, clarify the mechanisms leading to this differential response.