How blood groups determine Covid risk

Thursday October 22 2020
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As the new coronavirus disease (Covid-19) persists and spreads globally, it is allowing scientists to study condition and better understand how it affects people.

The prolonged existence of the disease has made it possible for health experts to study various individuals that have been affected by the condition.

This is helping them to solve the puzzle about the seemingly selective nature of the disease, which appears to affect some people more than the others.

Over the past months, many reasons have been given to explain the differences in the impact of the condition among various people.

So far, health experts have noted that people’s vulnerability to the disease and its severe symptoms are influenced by age, presence of pre-existing medical conditions and weakened immunity.

A new entrant into this group is blood type, which based on emerging research, appears to predict the risk and complications of Covid-19 infection.


Reduced risk

Numerous studies are increasingly producing evidence showing that there may be an association between blood type and vulnerability to Covid-19.

However, health experts note that additional research is needed to better understand why and what these findings mean for patients.

They also note that all people, irrespective of their blood type, should still strongly abide by the Covid-19 prevention strategies — such as washing hands with soap, social distancing and mask-wearing — since no one is immune to the disease, even if they appear to have a reduced risk of infection due to their blood group.

Recently, two new studies published in the Blood Advances Journal indicated that people with blood type O have a reduced risk of getting Covid-19.

According to the papers, these individuals are also less likely to suffer from severe outcomes of the condition, including organ complications, should they get sick.

In one of the studies, the researchers compared records from the Danish health registry of more than 473,000 individuals tested for Covid-19 to data from a control group of more than 2.2 million people from the general population.

Among the patients who had tested positive for Covid-19, they found fewer people with blood type O and more people with A, B, and AB types.

No significant difference was found in the rate of infection between these three blood types.

The research indicated that individuals with blood types A, B, and AB were also at higher risk of having blood clots inside their blood vessels and suffering from cardiovascular disease.

The two complications are common conditions that affect people hospitalised with the coronavirus disease.

“The study results suggest that people with blood types A, B, or AB may be more likely to be infected with Covid-19 than people with type O,” the researchers concluded.

They noted that the findings remained the same, even after they took into consideration differences in ethnicities.

“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 Dr Torben Barington, the study’s lead author from the Odense University Hospital and the University of Southern Denmark.

In the second study, the researchers examined data from 95 critically ill Covid-19 patients hospitalised in Vancouver, Canada.

They found that patients with blood groups A or AB were more likely to require mechanical ventilation, suggesting that they had greater rates of lung injury from Covid-19. These patients were also more likely to require dialysis for kidney failure.

While people with blood types A and AB did not have longer overall hospital stays than those with types O and, they did remain in the intensive care unit (ICU) for a longer average time.

This signalled a greater Covid-19 severity level.

“Together, these findings 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,” noted the researchers.


Future studies

“The unique part of our study is our focus on the severity effect of blood type on Covid-19. We observed this lung and kidney damage, and in future studies, we will want to tease out the effect of blood group and Covid-19 on other vital organs,” said Dr Mypinder Sekhon, the author of the study from the University of British Columbia.

She stated: “Of particular importance, as we continue to traverse the pandemic, we now have a wide range of survivors who are exiting the acute part of Covid-19, but we need to explore mechanisms by which to risk stratify those with longer-term effects.”

The link between blood type and complications arising from the coronavirus disease complications can, therefore, go a long way in enabling doctors to identify patients who are more likely to need long-term care.

Blood types are determined by the presence or absence of certain protein molecules, known as antigens, which are found on the surface of red blood cells. They are inherited genetically through parents.

The protein molecules, known as A and B antigens, correspond to the respective blood groups. People with blood group O have neither antigen