Two different studies published on October 16, 2020 in the journal Blood Advances, by the American Society of Hematology have said in their findings that the population with blood group ‘O’ are at lower risk of contracting the Covid-19 or SARS-CoV-2 infection. People with blood types ‘A’, ‘B’, or ‘AB’ may be at a higher risk of getting infected with Covid-19 than people with type ‘O’.
In the first study the researchers lead by Dr Torben Barington, of Odense University Hospital, had collected the information from the Danish health registry data with a population of 2.2 million. People were tested by ‘real-time polymerase chain reaction’ for COVID 19 infection. Among the 473,654 people who were eligible for the test, 7,422 were positive and 466,232 were negative.
As per the findings of the study, the rates of infection of the virus in blood types ‘A’, ‘B’ and ‘AB’ were high and similar. There were fewer COVID 19 positive cases in those with blood type ‘O’. Researchers considered ethnicity as a factor for blood group distributions however there were no change in the trends.
Dr Torben Barington stated that it was really essential to consider a strong control group as the blood type may vary between different ethnic groups. That was the reason they had considered Denmark for their study as it is a small and ‘ethnically homogeneous’ country. The study concluded that there was a slight, but statistically significant, the difference in blood group distribution between the SARS-CoV-2- [negative] individuals and the reference population.
The second study was conducted by researchers led by Dr Mypinder Sekhon, of the University of British Columbia. Here the researchers examined 95 critically ill COVID 19 patients of hospital in Vancouver in Canada.
Here the researchers observed that COVID 19 patients with blood types ‘A’ and ‘AB’ were at increased risk and required mechanical ventilation and prolonged stay in the intensive care unit. However patients with blood types ‘O’ and ‘B’ showed exhibited lesser severity in comparison to blood types ‘A’ and ‘AB’. Blood types ‘A’ and ‘AB’ had greater rates of lung injury and kidney failures because of COVID 19.
Although these new studies provide evidence of a potential link between blood type and vulnerability to Covid-19, additional research is needed to better understand why and what it means for patients. Also there were many limitations in these studies.
Studies published earlier, which were inconclusive also suggested that the prevalence of initial infection was higher among blood types ‘A’ and ‘B’, lower among blood types ‘AB’ in comparison to blood type ‘O’.