We have  antibodies of various kind. Antibodies againt various viruses, bacteria, other pathogen, tumors, many molecules like blood group antigen which defines the blood group of an individual. Many antibodies develop after we get infected as our immune response for protection. In case of blood group, people have antibodies for the group antigen they dont have. Thats y people with blood group AB dont have antibody for antigen A And B and can recieve blood from other blood groups. This statment is regarding only blood group. It doesnt mean u dont have  antibodies. And for Covid- u will develop antibodies againt covid virus after either getting infected or by vaccination.

AB,A,B and O blood group and it's antibodies is related to blood transfusion and if incorrect blood given :Mis-match transfusion. This is the work of RBC :red blood cell. Early studies regarding people with AB and B blood group by CSIR, say that these people are more prone to developing symptomatic infection while others may remain asymptomatic. Immunity is the work of WBC white blood cell which are the same in all humans, whatever be the blood group. These studies (by CSIR) are in the early phase (done on small group of people) and cannot be extrapolated to the entire human population. Hence do not be alarmed by this research.

Hello, basically AB blood group means antigen A and antigen B both are present on surface of red blood cells. Persons with AB blood group don't possess antibodies related to those respective antigens A and B. It doesn't mean they don't have antibodies at all. Immunity status of these people remains the same more or less corresponding to those of similar age/race/sex. You can fight against covid.

Antibodies again A n B antigen that we identify for blood grouping. Not antibodies in general

Antibodies formed for fighting against Infections are different from those antibody related to RBC surface antigen. Antibody formed against corona is from plasma cells and not red blood cells.