SALT LAKE CITY – Blood group does not influence the risk of contracting COVID-19 or developing a severe case of it, researchers from Intermountain Healthcare and other institutions have determined.
Their findings, published in the Journal of the American Medical Association earlier this month, counter previous previous global studies and research that suggested the blood type was a factor in why some people had more symptoms of COVID-19 than others.
“I think it’s important because it was really one of our main goals for us to identify patients at higher risk and to build risk scores,” said Dr. Jeffrey Anderson, a cardiologist and researcher at Intermountain Heart Institute Medical Center, and the study’s lead researcher.
Hospitals use all sorts of possible risks to determine whether or not someone should be hospitalized or what other care they should receive. The results of the study indicate that the blood group ABO is not a necessary factor for risk assessment.
Anderson explained that the study was determined by many unknowns in COVID-19. Medical professionals around the world have had little or no answers as to why some people get sicker than others. If he could solve the puzzle, then he could help provide better treatment to patients.
The data identified the elderly, as well as people with high obesity, diabetes, high blood pressure and pre-existing lung or heart disease. But since COVID-19 devastated China and Europe before the United States, global researchers have received an advance on other potential factors.
A study in China earlier this year sparked Anderson’s interest. He suggested that the blood type played a role in contracting COVID-19. Specifically, he suggested that those with blood group A have a higher risk of contracting COVID-19, and those with blood group O have a lower risk of becoming infected.
Researchers in Italy and Spain then launched a study that suggested that the blood type did not influence the contraction of COVID-19, but influenced the severity of a new case. In a somewhat similar result, the research suggested that blood group A led to more severe cases, and type O resulted in less severe results. It is unclear how many medical professionals have relied on these studies in how they treated COVID-19.
“We started to take an interest in this and we wondered if we should look into this as well, especially since there have been other reports that have had variable results,” Anderson said. “There was one in Denmark who said it was infectious, but not the severity of the disease, and then here in the US, New York and Boston … where there was no risk association.”
Thus, researchers from Intermountain Healthcare, the University of Utah School of Medicine and Stanford University tried to confirm the conclusions of the first studies.
They examined the results of 107,796 people tested for COVID-19 in Utah, Idaho and Nevada between March 3, 2020 and November 2, 2020. Anderson said the healthcare database provided a gold mine for researchers because they -provided to patients. “COVID-19 test results and their blood groups. He also provided information on how serious a case had become if someone was hospitalized.
About 10.6% of the nearly 108,000 people involved in the study tested positive for COVID-19, according to the data. Distributed by blood groups, the researchers found that the percentage of people who tested positive for COVID-19 essentially reflects the percentage who tested negative.
Blood group A, for example, accounted for 39.6% of positive results, but also 40.4% of negative results. Type B accounted for 9% of the positive and 9.3% of the negative. Type AB represented 3.2% positive and 3.3% negative, while type O represented 48.1% positive and 47.1% negative.
“There was no relationship between the ABO type and the risk of being infected,” Anderson said.
Similar patterns have emerged in cases of hospitalization and intensive care. Of the 11,468 positive cases, 2,326 were hospitalized; and 706 of the hospitalized arrived in the ICU.
Again, blood type accounted for 38.6% of hospitalizations and 39.9% of outpatients. It accounted for 36.4% of ICU stays and 39.5% of non-ICU hospitalization cases.
Type B accounted for 8.8% of hospitalizations and 9.1% of non-hospitalizations, as well as 8.6% of intensive care cases and 8.9% of non-therapeutic cases. Type AB accounted for 3.4% of hospitalizations and 3.1% of cases that did not require hospitalization; accounted for 2.8% of ICU cases and 3.6% of cases where ICU was not required.
Finally, 49.2% of hospitalizations involved people with type O blood, compared to 47.9% of cases where no hospitalization was needed; it also accounted for 52.1% of all data-intensive cases in the data, compared with 48% of the lack of hospitalization.
The results were somewhat surprising to researchers, especially as studies over the years have found links between type A blood and the risk of heart attack, Anderson said.
“I entered this study believing that we would probably validate or verify the reports of a relationship, but we did not find any,” he said.
This does not mean that the research did not find other connections. The data confirmed theories that older people, men and those in minority communities have a higher risk of contracting COVID-19 or developing severe COVID-19 disease.
I think it is extremely important to learn all we can about this virus so that we can fight it to the best of our ability.
–Dr. Jeffrey Anderson, cardiologist and researcher at the Intermountain Heart Institute Medical Center
Anderson added that it is also possible that the results will be regional. There is potential that other factors have led other global regions to find different results.
“Blood type varies in frequency between different populations and so on,” he said. “There may be different associations with the blood type that explain some of the other results, different results from other areas.
In other words, blood groups could be linked to other characteristics that cause disease or endanger people, he continued. “This is called an association and that’s different from what we would call a causal risk factor.”
For researchers like Anderson, finding a correlation between blood type and COVID-19 risks is one piece closer to solving the COVID-19 puzzle.
It adds to the growing list of articles learned since SARS-CoV-2 and COVID-19 were first identified in late 2019. Because SARS-CoV-2 was a new coronavirus, it meant that medical experts began with the same knowledge as anyone else about how it spreads and how it affects people.
“I think it’s extremely important that we learn everything we can about this virus so that we can fight it to the best of our ability,” Anderson said. “We haven’t passed yet. It’s great to see the light at the end of the tunnel, to see our numbers go down, but this will still be with us at some level, I think, for the next few months and maybe years.
“The more we can learn about it, the better we feel.”