Your blood type doesn’t affect your odds of catching COVID-19, Intermountain study says

Another study, led by University of Utah doctors, looks at the link between COVID-19 and a particular kind of stroke.

(Francisco Kjolseth | Salt Lake Tribune file photo) Blood samples to be tested for coronavirus antibodies are stored in refrigerators inside the Huntsman Cancer Institute Cancer Screening bus while in Park City on Wednesday, May 6, 2020, as part of a mobile testing site. A new study by researchers at Intermountain Healthcare found no correlation between a person's blood type and whether they were more likely to catch COVID-19.

Your blood type won’t have much effect on whether you catch COVID-19, or have a severe case of the disease, according to a new study by researchers at Intermountain Healthcare — a conclusion that contradicts earlier research.

“It’s wonderful to know your blood type,” Dr. Jeffrey L. Anderson, a physician at Intermountain Medical Center’s Heart Institute in Murray, said Thursday. “But knowing what your blood type is is not something that will protect you from COVID, or put you at higher risk.”

The researchers at Intermountain examined the outcomes of more than 100,000 patients who were tested for the coronavirus. Connections between specific blood types and the virus “are unlikely and will not be useful factors associated with disease susceptibility or severity,” the study concluded.

Anderson was the lead author of the study, which was published earlier this month in JAMA Network Open, a sister publication to the prestigious Journal of the American Medical Association.

The 100,000 cases came from Intermountain’s database of patients, largely from Utah but also from Idaho, Nevada and other states, Anderson said.

A pair of studies published last October in the online journal Blood Advances suggested that people with type O blood were at lower risk of infection from the coronavirus — while people with type A or AB blood had a higher risk of more severe illness. Other studies early in the pandemic from China and Europe had similar findings, though other researchers warned the sample sizes of those studies were too small to be conclusive.

“Those other studies were different among themselves, too,” Anderson said, noting that some covered the susceptibility of catching the virus while others looked at how severe the disease was. “When you see different results from different studies, you wonder: Is this a result of the play of chance? That’s why you need replication,” Anderson said.

In some parts of the world, Anderson said, differences in blood type may be associated with other genetic factors — and it could be those factors, not a person’s blood type, that caused the difference in outcomes that showed up in those studies.

For now, Anderson said, health experts continue to see the same factors that indicate a person is more likely to get COVID-19 or have a more severe battle with the disease. Those include a person’s age, their sex — men tend to have a harder time with COVID-19 than women — and whether they are overweight or have pre-existing conditions such as blood pressure, diabetes, or a history of heart or lung disease, he said.

Meanwhile, a national study led by University of Utah researchers found that people who have a hemorrhagic stroke are 2.4 times more likely to die if they also have COVID-19.

“This is one of the first studies to document that, in patients with hemorrhagic stroke who have comorbid COVID-19, there is a significantly elevated risk of in-hospital death,” Dr. Adam de Havenon, assistant professor of neurology at University of Utah Health, and senior author of the study, said in a statement.

The study, published Wednesday in the journal PLOS ONE, found that racial and ethnic minorities, and those who suffered from obesity and diabetes, were among the most vulnerable.

Hemorrhagic strokes happen when a blood vessel ruptures in the brain, bleeding into the surrounding brain tissue. They are less common than ischemic strokes, which happen when an artery supplying blood to the brain is blocked.

Recent studies have suggested that COVID-19 increases the risk of ischemic strokes. Little is known, however, about the link between COVID-19 and hemorrhagic strokes.

For this study, de Havenon and his colleagues examined medical records from 568 hospitals nationwide, employing a commonly used health care database. They compared admissions for more than 23,000 patients with hemorrhagic stroke in 2019, without COVID-19, to 771 patients admitted in 2020 with COVID-19 who also had hemorrhagic strokes before or after they were admitted to the hospital.

The 559 patients who had COVID-19 and an intracerebral hemorrhage — where there is bleeding into the brain tissue — had a higher in-hospital death rate: 46%, compared to 18%. They also had longer hospital stays (21 days, compared to 10 days) and longer stays in intensive care (16 days, compared to six days). Only about 1 in 4 patients with both COVID-19 and an intracerebral hemorrhage had a “favorable discharge outcome,” meaning going home or to a rehab center; for the 2019 patients with an intracerebral hemorrhage, half had favorable outcomes.

The study found similar patterns among the 212 patients with a subarachnoid hemorrhage, which is when a damaged artery bursts on the brain’s surface.

In both types of hemorrhagic strokes, patients who also had COVID-19 were also more likely to be put on a respirator, and have heart problems, kidney failure or pulmonary embolisms.

Nearly half the patients admitted with COVID-19 had their hemorrhagic strokes after they were admitted to the hospital. The reason is unclear, de Havenon said, but patients admitted with COVID-19 were more likely to be given drugs that prevent blood clotting — which could increase the risk of hemorrhagic strokes. That phenomenon will be the subject of future studies, de Havenon said.

Dr. Ramesh Grandhi, a neurosurgeon at University of Utah Health and another author on the study, said the study could help doctors tailor treatments for patients who have both COVID-19 and hemorrhagic strokes.

“Sometimes, as doctors, we see things on a day-to-day, patient-to-patient level that doesn’t help us very much,” Grandhi said in a statement. “But seeing a larger data set across a vast hospital network really allows us to see that these aren’t just isolated incidences.”