The University of Louisville Journal of Respiratory Infections



Background: The potential association of the ABO blood group with the risk of COVID-19 and its severity has attracted a lot of interest since the start of the pandemic. While a number of studies have reported an increased risk associated with blood type A and a reduced risk with type O, other studies have did not found a significant effect. This study aimed to define the prevalence of different ABO blood groups in hospitalized COVID-19 patients in the Louisville, KY area and to investigate whether an association exists between the blood group and disease severity.

Methods: This was a retrospective observational study of 380 patients with SARS-CoV-2 infection hospitalized to eight of the adult hospitals in the city of Louisville. Patients were divided into four different groups according to their ABO blood type. Demographic characteristics and clinical variables, including laboratory data as well as clinical outcomes were compared.

Results: Type O was the most common blood group among the hospitalized patients (51%) followed by type A (31%), B (14%) and AB (4%). The observed blood group distribution among the patients was not significantly different from the distribution expected when compared to a population of similar racial/ethnic composition. No significant associations were found between the blood group and comorbidities, inflammatory biomarkers as well as with recorded outcomes, including the mortality rate and the length of the hospital stay.

Conclusions: The data from hospitalized patients in Louisville is is not consistent with the ABO blood group having a significant effect as a risk or severity factor for COVID-19, but it is representative in COVID-19 or its severityof its prevalence among different racial/ethnic populations.


The authors received no specific funding for this work.



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Creative Commons Attribution 4.0 License
This work is licensed under a Creative Commons Attribution 4.0 License.



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