A study about blood differences and the risk for COVID-19

Question

On healthline it's mentioned a recent study that came out of Wuhan, China; it’s published on a website, but hasn’t yet been reviewed by peers.

In the study, scientists looked at the blood types of 2,173 people who had been diagnosed with COVID-19 and compared that with the blood types of the general population in that region.

They found that in the normal population, type A was 31 percent, type B was 24 percent, type AB was 9 percent, and type O was 34 percent.

In those with the virus, type A was 38 percent, type B was 26 percent, type AB was 10 percent, and type O was 25 percent.

The researchers concluded that “blood group A had a significantly higher risk for COVID-19 compared with non-A blood groups. Whereas blood group O had a significantly lower risk for the infectious disease compared with non-A blood groups.”

In 'non-medical' or easy to follow terms/explanations, Why is that?

Why does blood type A is more at risk?

and Why does blood type O has less risk?

Thank you in advance

Answer 1

In simpler terminology than used in the paper referred to, the observation has been made before that there is a blood group susceptibility to certain viruses, and that SARS appeared to affect blood group O individuals less than group A.

Group O individuals possess antibodies against the antigens displayed by group A individuals on their cells. These antibodies, anti-A, interfered with the binding of the SARS-CoV-2 spike protein to the ACE2 receptor - like a form of neutralizing antibody or natural protection. Their small studies suggested that Group O individuals had 60% of the risk of the full population and Group A individuals an increased risk of 120%. AB Blood group risk ranged from 148-200% increased risk.

Whether that is clinically useful remains to be seen. Could pooled immunoglobulin from Group O individuals help infected sick Covid-19 patients? Would any vaccine directed against this region of the virus be ineffective in Group A/B individuals because they would be trying to create a vaccine against self antigens?