The researchers also wrote that their study's findings are congruent with a recent study of 1 980 Covid-19 patients that also demonstrated a link between ABO blood type and disease severity.
Two studies published this week suggest that people with Type O have a lower risk of getting the coronavirus, as well as a reduced likelihood of getting severely sick if they do get infected. The first study carried out in Denmark on 473,654 people who were tested for Covid-19 between February and July found that only 7,422 tests with blood type O were positive. The researchers also noted that people with blood types A and AB did not have longer overall hospital stays.
While no significant difference in the rate of infection was found between blood groups "A", "AB", and "B" types, the study did suggest that the first two are associated with an increased risk of severe clinical outcomes of the infection, the agency said in its report. One looked at 95 critically ill COVID-19 patients at hospitals in Vancouver, Canada, between February and April.
Most people fall into one of four blood types: A, B, AB, or O. In the United States, the most common blood types are O and A. However, the United States still has the highest number of infections and deaths from Covid-19.
The new studies about blood type and coronavirus risk align with prior research on the topic. The findings also reveal patients across different ethnic groups continue to show fewer infections if they have O blood. This means that it's not clear how the relationship between blood type and Covid-19 works and any link may be coincidental.
Most of the 36 hospitalised cases are stable or improving, while none is in critical condition in the intensive care unit.
The researchers observed that patients with these blood types are more likely to be put on mechanical ventilation.
Previous studies have indicated similar results in patients with blood type O.
That's lower than the prevalence of Type O in a population of 2.2 million Danish people, 41.7 percent, so the researchers determined that people with Type O blood had disproportionately avoided infection.
It is also important to note that people with type O blood can and do become infected. "And if you're blood group O, you're not free to go to the pubs and bars".
Lead author of the study, Dr Mypinder Sekhon, of the University of British Columbia, said: "The unique part of our study is our focus on the severity effect of blood type on COVID-19".