However, people with types A and AB were not so lucky, as scientists found that they were more likely to suffer more severely than people from the other two blood groups (O and B). Blood groups are defined by their numbers of antigen and antibody proteins. Type O is the most common across the world.
One of the studies was carried out by a team of researchers from Odense University Hospital and the University of Southern Denmark. They compared Danish health registry data from over 473,000 people who were tested for Covid-19 to a control group of more than 2.2 million from the general population.