It was already written months ago that bloodgroup O is the group with least Covid infections and A the most. O has a more aggressive immune system and A has quite a lazy immune system. What should also be considered, non-secretors and secretors are definitely a factor, in my eyes. Non-secretors also have a weak immune response. Maybe bloodgroup A non-secretors should take special care. Our pharmacist told me to take 2 cloroquins every three weeks, uses statins every second day, and take bloodthinner like aspirin every day. To try and prevent getting covid.