Two recent studies suggest that blood type O is associated with a lower risk of SARS-CoV-2 infection and severe COVID-19 disease compared with other blood types.
Danish researchers found that among 7,422 confirmed COVID-19 cases who were tested between February and July, 38.4% were blood type O and 44.4% were blood type A. The reported prevalence of blood type O in the sample was lower than the actual prevalence of blood type O, 42%, in a wider reference population of over 2 million people.
The second study looked at 95 critically ill COVID-19 patients who were hospitalised in Vancouver, Canada, between February and April. They found that patients with blood type O or B spent 4.5 days less in the intensive-care unit, on average, compared with blood types A or AB. 61% of patients with blood type O or B required a ventilator compared to 84% those with type A or AB. The latter group was also more likely to require dialysis.
Why it matters: Whilst the study findings, which are in alignment with research published earlier this year, do not imply that people should change their lifestyle according to their blood type, understanding the mechanistic association between different blood types and COVID-19 could be used towards how specific patients are treated.