People with a type O blood are 12 per cent less likely to catch the coronavirus than other blood types, a study has found.
It also reveals that those with a negative blood type (O-, A-, B- or AB-) are, on average, 21 per cent less likely to get the virus than people with a positive type.
Individuals with type O or negative blood are also 13 per cent and 19 per cent less likely to develop severe symptoms or die, respectively.
In the UK, around 15 per cent of the population have a negative blood type and almost half (around 48 per cent) are type O.
Around one in eight people (13 per cent) are O-, which are 26 per cent less likely to get infected and 28 per cent less likely to develop severe symptoms or die.
Researchers from the Institute for Clinical Evaluative Sciences in Toronto studied 225,556 people who had a blood test between 2007 and 2019 and a Covid swab this year.
Every person has one of four blood types, either A, B, AB or O and the difference in blood groups depends on the presence or absence of specific attachments on red blood cells called antigens.
There are two antigens, A and B. An individual can have one of these, both (AB) or none (O).
The presence, or absence, of these molecules dictates what blood type a person is.
There is another antigen, but there are not four possibilities, just two, and this is called the Rhesus antigen.
Researchers analysed the anonymised medical records of more than 225,000 Covid patients from Ontario and found 36.3 per cent had blood type A, 4.5 per cent had type AB, 14.9 per cent had type B, and 44.3 per cent had type O.
Statistical analysis accounted for all other variables and comorbidities and found the adjusted relative risk for SARS-CoV-2 infection is 15 per cent higher in type AB than in type A.
Infection is five per cent less likely in type O than A, but when compared to all blood groups, this grows to 12 per cent, the researchers found.
