A research paper published in March raised an interesting question: Could blood types play a role in COVID-19's severity? Right now there are scientific contradictions that make it impossible to definitively answer that question.
The initial report, conducted by Chinese researchers, compared COVID-19 outcomes in 2,173 patients and looked to see if there were patterns relating to blood types.
“The results showed that blood group A was associated with a higher risk for acquiring COVID-19 compared with non-A blood groups,” the report’s abstract reads.
While an “association” doesn’t necessarily mean a direct link, this report led to multiple other studies that have been published in recent weeks.
The VERIFY team took a look at the most recent and what they found.
STUDIES THAT FOUND AN ASSOCIATION:
In June, a pre-print study was published that detailed the work of Italian and Spanish researchers. They gathered data on 1,610 COVID-19 patients who had severe outcomes and compared their results to their blood types.
In their abstract, the researchers wrote that “analysis showed a higher risk for A-positive individuals ... and a protective effect for blood group O.”
As of the writing of this VERIFY article, this study had not been peer-reviewed and was still in “pre-print.”
On July 21, Columbia University researchers published another pre-print study with related findings. They analyzed 7,770 people who had been tested for SARS-CoV-2 and looked for any association between blood type and outcome.
Their abstract reads that they “find evidence of overall association with ABO blood groups and a beneficial association between Rh-negative blood groups and both infection status and death.”
STUDIES THAT SAY THERE IS NO LINK:
On July 17, Researchers at Harvard Medical School published research in the Annals of Hematology. They analyzed data on 7,648 patients who received COVID-19 testing.
“Blood type is not associated with a severe worsening of symptoms in people who have tested positive for COVID-19, report Harvard Medical School researchers based at Massachusetts General Hospital,” a press release reads.
While their study did not support the idea that blood type is linked to COVID-19 severity, it did find a different possible association. It reads that “symptomatic individuals with blood types B and AB who were Rh positive were more likely to test positive for COVID-19, while those with blood type O were less likely to test positive.”
There isn’t one. As frustrating as it may be for people wanting a definitive answer on this question, the science is not conclusive right now. That doesn’t mean any of these studies are inherently wrong or flawed, it just means that more research will have to be done.