Mass General Hospital study finds no relationship between blood type and severity of COVID-19

BOSTON – Blood type is not associated with a severe worsening of symptoms in people who have tested positive for COVID-19, researchers from Massachusetts General Hospital (MGH) have reported, dispelling previous reports that suggested a correlation between certain blood type and COVID-19. A study published in Annals of Hematology did find, however, that symptomatic individuals with blood types B and AB who were Rh+ were more likely to test positive for COVID-19, while those with blood type O were less likely to test positive.

“We showed through a multi-institutional study that there is no reason to believe being a certain ABO blood type will lead to increased disease severity, which we defined as requiring intubation or leading to death,” said Anahita Dua, MD, MS, MBA, investigator in the Division of Vascular and Endovascular Surgery at MGH and senior author of the study. “This evidence should help put to rest previous reports of a possible association between blood type A and a higher risk for COVID-19 infection and mortality.”

The explosion of COVID-19 in all corners of the world sent scientists scrambling to find characteristics that might render individuals more susceptible to the virus, as well as risk factors that might intensify its severity and progression. This frenzied activity resulted in numerous theories and reports about the association between COVID and blood type from the scientific community globally which tended to raise more questions than they answered.

MGH launched its own investigation by drawing on the massive database of the Mass General Brigham (formerly Partners HealthCare) system’s Research Patient Data Registry (RPDR). A study population of 1,289 symptomatic adult patients who tested positive for COVID-19, and had their blood group documented, was culled from more than 7,600 symptomatic patients across five Boston-area hospitals, including MGH and Brigham & Women’s Hospital, treated from March 6^th to April 16^th of this year. The statistical analysis determined the independent effect of blood type on intubation and/or death of these infected patients.

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

“Inflammation is a particularly important finding because prevailing scientific thought is that COVID-19 wreaks havoc on the body through systemic inflammation, which can lead to morbidity and death,” explains Dua. “We found, however, that inflammation markers remained similar in infected patients regardless of their blood type.”

An intriguing finding from the MGH researchers was that there appeared to be a greater chance of people with blood types B and AB who were Rh+ testing positive for the virus. Even stronger evidence was assembled by the team that symptomatic people with blood type O were less likely to test positive. “These findings need to be further explored to determine if there is something inherent in these blood types that might potentially confer protection or induce risk in individuals,” says Dua.

For now, though, the researchers are confident that their principle finding – that ABO blood typing should not be considered prognostic in patients who acquire COVID-19 – will help to debunk the kinds of clinically unfounded rumors and misinformation that can readily gain traction in the midst of a pandemic, and in some cases become part of accepted medical practice.

Senior author Dua is also an assistant professor of surgery Harvard Medical School, director of the Vascular Lab, and associate director of the Wound Care Center at MGH. Lead author Christopher Latz, MD, MPH, and co-authors Charles DeCarlo, MD along with Laura Boitano, MD MPH and C.Y. Maximillian Png MD, are vascular surgery residents at MGH. Other co-authors include Matthew Eagleton, MD, chief of the Division of Vascular and Endovascular Surgery at MGH, and Mark Conrad, vascular surgery program director at MGH.

About the Massachusetts General Hospital
Massachusetts General Hospital, founded in 1811, is the original and largest teaching hospital of Harvard Medical School. The MGH Research Institute conducts the largest hospital-based research program in the nation, with an annual research budget of more than $1 billion and comprises more than 8,500 researchers working across more than 30 institutes, centers and departments. In August 2019 the MGH was once again named #2 in the nation by U.S. News & World Report in its list of "America’s Best Hospitals."