Since the early days of the COVID-19 pandemic, scientists have explored whether blood types affect vulnerability to the virus. Research confirms a link: individuals with blood type O appear to have a lower infection risk. A study by researchers at Shenzhen University found that type O individuals face a 33% reduced chance of infection. In contrast, those with type A have a 20% higher risk compared to types B and AB. But with Omicron's rapid spread, does this protection still apply?
Jacques Le Pendu, research director at Inserm in Nantes specializing in immunology, investigated this connection in a study published on January 5, 2022, in Frontiers in Microbiology. "We examined couples where one partner was infected and symptomatic, sharing close quarters for maximum exposure risk," he explains. "By assessing blood types and transmission direction, we found that in cases of blood group incompatibility, the uninfected partner's risk of developing symptomatic COVID-19 dropped by half." In essence, blood type incompatibility acts as a partial shield against transmission.
While type O offers some protection, it is not absolute—those with this blood type can still contract COVID-19. However, evidence suggests better outcomes. "Data supports reduced severity in type O patients, particularly at advanced stages," notes Le Pendu. This protective effect is partial: type O individuals may still require hospitalization but have a higher chance of recovery—and potentially faster.
Protective measures like masking, distancing, and hygiene remain critical regardless of blood type. Other factors—age, diabetes, comorbidities—significantly influence infection risk and severity. Le Pendu's findings applied to earlier variants; data on Delta and Omicron is limited. "We lack specifics on Omicron," he acknowledges. "Given its high contagiousness, this protection may diminish."
