“Although we saw a statistically significant association between blood group and severe disease or death, it was also assumed that we had correctly identified severe illness associated with Covid-19 ,” the authors wrote. Their findings indicate that O and Rh-negative blood groups were associated with a slightly lower risk for SARS-CoV-2 infection as well as severe Covid-19 illness or death. “Our goal was to determine whether ABO and Rh blood groups could be associated with a risk for acquiring a SARS-CoV-2 infection and developing a severe Covid-19 illness,” said study authors from the University of Toronto in Canada.Īccording to the study, out of the more than 200,000 tests that were examined, 1,328 of them were diagnosed with severe Covid-19 illness or death, with higher probabilities among AB and B blood groups, as well as those who were Rh-positive. Median ICU stay length was also longer for A or AB patients compared with O or B patients (13.5 days vs 9 days, P=0.03).Having O and rhesus-negative or Rh-, blood was associated with a slightly lower risk for Covid-19 infection and severe illness or death, say researchers.įor the results, published in the journal Annals of Internal Medicine, the research team examined 225,556 people who tested their blood type from January 2007 to December 2019, and who later had a Covid-19 lab test. Similar figures were seen for patients requiring continuous renal replacement therapy (32% vs 9%, P=0.04). A significantly higher proportion of A/AB patients required mechanical ventilation versus O/B patients (84% vs 61%, respectively, P=0.02). 21 to April 28, identifying 95 COVID-19 patients admitted to an ICU with known ABO blood type.Īmong these patients, 57 were group O or B, while 38 were group A or AB.

They collected data from six metropolitan Vancouver hospitals from Feb. 'If ABO blood groups play a role in determining disease severity, these differences would be expected to manifest within multiple organ systems and hold relevance for multiple resource-intensive treatments, such as mechanical ventilation and continuous renal replacement therapy,' Sekhon and colleagues wrote. These authors also cited research that found that blood groups were linked to virus susceptibility, but that the relationship between SARS-CoV-2 infection severity and blood groups remains 'unresolved.' However, COVID-19 appears to be a multisystem disease with renal and hepatic manifestations. Researchers also observed how blood groups are 'increasingly recognized to influence susceptibility to certain viruses,' among them SARS-CoV-1 and norovirus, adding that individuals with A, B, and AB blood types may be at 'increased risk for thrombosis and cardiovascular diseases,' which are important comorbidities among patients hospitalized with COVID-19.ĪBO and RhD blood group information was available for 473,654 individuals who were tested for SARS-CoV-2 from February 27 to July 30, as well as for 2,204,742 individuals not tested for SARS-CoV-2 as a reference. They pointed to the recent research that blood type plays a role in infection, noting the lower than expected prevalence of blood group O individuals among COVID-19 patients.

Limitations to the data include that ABO blood group information was only available for 62% of individuals, and that the sex of the testing population was skewed, with women accounting for 71% who tested negative and 67% who tested positive. However, there was no increased risk for COVID-19 hospitalization or death associated with blood type, the authors wrote in Blood Advances.

A negative blood type covid