A large study adds to evidence that people with type O or Rh−negative blood may be at slightly lower risk from the new coronavirus.
Among 225,556 Canadians who were tested for the virus, the risk for a COVID-19 diagnosis was 12% lower and the risk for severe COVID-19 or death was 13% lower in people with blood group O versus those with A, AB, or B, researchers reported on Tuesday in Annals of Internal Medicine.
People in any blood group who were Rh-negative were also somewhat protected, especially if they had O-negative blood. People in these blood type groups may have developed antibodies that can recognize some aspect of the new virus, coauthor Dr. Joel Ray of St. Michael’s Hospital in Toronto told Reuters.
“Our next study will specifically look at such antibodies, and whether they explain the protective effect,” Ray said. Whether or how this information might influence COVID-19 prevention or treatment is still unclear.