There's more evidence that blood type may affect a person's risk for COVID-19 and severe illness from the disease. The findings are reported in a pair of studies published Oct. 14 in the journal Blood Advances. In one, researchers compared more than 473,000 people in Denmark with COVID-19 to more than 2.2 million people in the general population. Among the COVID-19 patients, there was a lower percentage of people with blood type O and higher percentages of those with with types A, B and AB. The findings suggest that people with A, B or AB blood may be more likely to be infected with COVID-19 than people with type O blood. Infection rates were similar among people with types A, B and AB blood. The other study included 95 critically ill COVID-19 patients hospitalized in Canada. Patients with type A or AB blood were more likely to require mechanical ventilation, suggesting that they had greater rates of lung injury from COVID-19. More patients with type A and AB blood required dialysis for kidney failure, the study added.