According to two new studies, people with blood type O may...

Research provides further evidence that blood type (also known as blood type) may play a role in a person’s susceptibility to infection and their likelihood of having a severe attack of the disease. The reasons for this association are not clear and further research is needed to determine what effect this may have on patients.

Studies add to growing evidence

A Danish study found that among 7,422 people who tested positive for Covid-19, only 38.4% were blood type O – although in a group of 2.2 million people who were not tested this blood type was 41.7% of the population.

In contrast, 44.4% of group A were positive, while in the wider Danish population this blood group accounts for 42.4%.

In the other study, researchers in Canada found that among 95 patients critically ill with Covid-19, a higher proportion with blood group A or AB – 84% – required mechanical ventilation than patients with blood group O or B 61%.

The Canadian study also found that patients with blood type A or AB had a longer stay in the intensive care unit, a median of 13.5 days, compared to patients with blood type O or B, who had a median of nine days.

“As a clinician… I keep it in the back of my mind when I look at patients and shift them. However, in terms of a definitive marker, we need repeated results in many countries showing the same thing, ”said Dr. Mypinder Sekhon, an intensive care physician at Vancouver General Hospital and author of the Canadian study.

“I don’t think this replaces other severity risk factors like age and comorbidities, etc.,” added Sekhon, who is also a clinical assistant professor in the Department of Intensive Care Medicine and the Department of Medicine at the University of British Columbia.

“If you are blood group A, you don’t have to panic. And if you are O blood type, you can’t go to the pubs and bars. ‚

No reason to worry

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.

It makes little difference to most people’s daily lives unless you need to have a blood transfusion. Also, people shouldn’t be overly concerned about the connection between blood type and Covid-19, said Dr. Torben Barington, senior author of the Danish newspaper and clinical professor at Odense University Hospital and the University of Southern Denmark.

“We don’t know if this is some kind of group O protection or if it’s some kind of vulnerability in the other blood groups,” he said.

“I think this is of scientific interest, and if we can figure out what the mechanism is, maybe we can use that proactively in relation to treatment.”

In the Danish study, the researchers analyzed data from Danish people who were tested between February 27 and July 30, and the distribution of blood types among these people was compared with data from people who had not been tested. They found that blood type was not a risk factor for hospitalization or death from Covid-19.

Both studies were published in the journal Blood Advances.

Although there are several theories, researchers do not yet know what mechanism could explain the connection between different blood types and Covid-19.

Sekhon said it could be explained by people with blood type O, who have less of an important clotting factor, making them less prone to clotting problems in the blood. Coagulation was a major reason for the severity of Covid-19.

Other possible explanations concern blood group antigens and how they affect the production of antibodies against infections. Or it could be linked to genes associated with blood types and their effect on receptors in the immune system.

“It’s a repetitive, interesting scientific observation that really warrants more mechanistic work,” he said.

“Important research question”

The results of the two new studies provide “more convergent evidence that blood type plays a role in a person’s susceptibility to Covid infection and their likelihood of a severe attack of Covid-19,” said Dr. Amesh Adalja, senior scientist at the Johns Hopkins University Center for Health Security in Baltimore, who was not involved in any of the studies.

A separate study published in the New England Journal of Medicine in June found genetic data in some Covid-19 patients and healthy people suggesting that those with type A blood were at higher risk of infection and those with type -O-blood a lower risk.

This earlier genetic study, coupled with the two new studies on Blood Advances, “suggests this is a real phenomenon that we are seeing,” said Adalja, whose work focuses on emerging infectious diseases.

“Although we are not yet ready to obscure this, it is clearly suggestive and we have not seen anything incompatible with it. The same pattern has emerged with the O blood group, which tends to stand out, ”said Adalja.

Adalja said that blood types and their susceptibility to various infections have already been studied in the medical literature. For example, research suggests that people with blood type O appear to be more prone to norovirus infections.

As for the novel coronavirus that is causing Covid-19, “We need to figure out the mechanism and understand it at the molecular level to be able to say for sure how this is happening – that this is really the O blood type and not something that kind of trace with O blood type, ”said Adalja.

“We’re seeing enough now that I think it’s an important research question that needs to be answered,” he said. “There is more science to be done here, but it seems to me that more evidence is building up to support this hypothesis.”