A preprint study published in March this year suggested that people with blood type A have a higher risk of acquiring Covid-19 compared with non-A blood groups, while another study published in June found that blood type O seemed to be more resistant against Covid-19 infection.
These findings, taken together, suggest that patients in these two blood groups may have an increased risk of organ dysfunction or failure due to COVID-19 than people with blood types O or B.
As part of the study, the team of researchers gathered Danish health registry data from more than 473,000 individuals tested for COVID-19 and compared it to data from a control group of more than 2.2 million people, as per a report by news agency IANS. A study published in July looking at patients in five major hospitals in the state of MA found that people with blood type O were less likely to test positive for COVID-19 than those with other blood types.
Which blood types put coronavirus patients in danger? Yet another earlier study by a US-based biotechnology company, 23andMe, said that people with O-type blood group are less likely to catch the COVID-19 infection. For example, people with type A blood produce different antibodies to people with blood type O. It's still not known, however, whether this has any significant effect on a person's ability to battle Covid-19.
Preliminary results from an ongoing study suggest that those with a certain blood type may have some protection against the novel coronavirus.
"It is very important to consider the proper control group because blood type prevalence may vary considerably in different ethnic groups and different countries", said study author Torben Barington, MD, of Odense University Hospital and the University of Southern Denmark. The interesting observation made in this study was that the patients with the blood group A and AB required more of the mechanical ventilation, as compared to the blood group O. Similar was the case with patients being admitted in the ICU. It also found that people with blood group AB were the most likely to test positive for COVID-19 infection, followed by blood group B and then blood group A.
Interestingly, blood groups, A and AB were also associated with complications post-hospitalization, such as myocarditis, lung injury and renal damage. This means that it's not clear how the relationship between blood type and Covid-19 works and any link may be coincidental.