There is some evidence that people with A, AB, or B blood types are more likely to have serious COVID infections than people with type O blood, which would explain in part why some ethnicities are more (or less) likely to get really sick or die.
This story is from a journal but is not written in technical jargeon.
And here’s another source.
The studies actually seem to show lower infection rates in people with group O, but increased severe outcomes in just the A and AB groups.
Also, just to mention that the Danish study in the first cite did not see a increase in mortality across blood groups once someone was infected, but that the (much smaller) study referenced as well in the second cite suggests there was.