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Does blood type influence COVID-19 risk?

FILE - In this Friday, June 12, 2020 file photo, a nurse uses a swab to perform a coronavirus test in Salt Lake City. (AP Photo/Rick Bowmer)

Studies suggest Type O blood reduces your COVID-19 risk, while Type A increases it

Reason for apparent correlation is unknown

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A Chinese study looking at the blood types of 2,173 patients found people with Type A blood were at a “higher risk for acquiring COVID-19” while those with Type O faced a “lower risk.”

The researchers, however, said theirs was an “early study with limitations.”

“It would be premature to use this study to guide clinical practice at this time, but it should encourage further investigation of the relationship between the ABO blood group and the COVID-19 susceptibility,” the researchers wrote in the study published in late March.

Since then, a study of thousands of patients in Italy and Spain found similar results, suggesting a “higher risk in blood group A” and a “protective effect in blood group O.”

Both studies have been released as pre-print, meaning they have yet to be peer reviewed.

Genetic testing company 23andMe released preliminary data from more than 750,000 participants in its study of the disease, finding people with Type O blood are nine to 18 per cent less likely to get COVID-19.

“While it is still very early in the study, 23andMe’s preliminary investigation into genetics seems to support these findings,” the company says on its website, referring to previous studies linking blood type with susceptibility to the novel coronavirus.

Dr. Stephen Hoption Cann, a professor at UBC’s school of population and public health, said, “there have been a few studies looking at this question and they do seem to consistently show that individuals with type O blood are less likely to be positive for COVID-19 infection when examining blood of hospitalized patients.”

“Why people with Type O blood are less likely to test positive is not known, but may be due to how the immune system responds to the virus,” he said.

In Canada, Cann said, 39 per cent of people have Type O blood and 36 per cent have Type A.

Cann said some research suggests individuals with rhesus positive blood are more likely to test positive. (In addition to lettered types, blood is either rhesus positive or negative.)

While there is mounting evidence for the correlation between blood type and COVID-19 risk, Cann said the studies do not suggest blood type influences the severity of sickness.

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