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Blood type and COVID-19: The reality behind the rumor

Does O negative blood make someone immune to COVID-19? No, the science is more complicated than that.

ARIZONA, USA — Editor's note: The video above is a VERIFY segment providing more answers to virus misconceptions. 

O negative blood has been linked with COVID-19 immunity since late 2020 when health officials worldwide began studies trying to make connections between blood typing and virus severity. 

Why the information can be misunderstood

The NIH reports people have questioned why most get mild cases of the virus while others fall into severe respiratory distress and even death after getting sick. 

Officials with the NIH also say there have been cases of young people, who are otherwise healthy, getting COVID-19 and becoming very ill. So why is that the case? 

According to the National Institute of Allergy and Infectious Diseases, virus severity is most often linked with genes. 

“The two stretches of DNA implicated as harboring risks for severe COVID-19 are known to carry some intriguing genes, including one that determines blood type and others that play various roles in the immune system,” the institute found. 

So how did O blood get linked with immunity?

Because certain genes were seen in individuals with both O blood carriers and less severe COVID-19 cases, it was assumed that there was a definitive link between the two factors. 

But the theory was disproved. 

Researchers from Harvard Medical School looked at a population of 1,289 symptomatic adults who tested positive for COVID-19 and recorded their individual blood types. 

“The large retrospective review showed no significant connection between blood type and worsening of the disease, between blood type and need for hospitalization, positioning requirements for patients during intubation, or any inflammatory markers,” the report found. 

Interestingly, the study found that people with type B positive and AB positive blood were more likely to test positive for the virus whereas symptomatic people with type O blood were less likely to test positive. 

But researchers say their study doesn't conclude that people of any blood type are susceptible to the virus than anyone other.

How the misinformation spread

Dr. Ricardo Correa, an endocrinologist from the University of Arizona’s College of Medicine, said that the rumors about blood type and immunity began on social media and spread quickly. 

“There is no way that they [people with O negative blood] could be immune to COVID because blood type is not related with how the virus affects the system,” Correa said. 

While some common links could be attributed to a decreased likelihood of severity, blood type as a singular factor would not make the difference. 

More resources

The full Harvard Medical report 

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