Immunocompetence is the ability of the body to produce a normal immune response following exposure to an antigen. Immunocompetence is the opposite of immunodeficiency or immuno-incompetent or immuno-compromised. Examples include:
There may be cases of overlap but these terms all describe immune system not fully functioning.
The US Centers for Disease Control and Prevention (CDC) recommends that household and other close contacts of persons with altered immunocompetence receive the MMR, varicella, and rotavirus vaccines according to the standard schedule of vaccines, as well as receiving an annual flu shot. All other vaccines may be administered to contacts without alteration to the vaccine schedule, with the exception of the smallpox vaccine. Persons with altered immunocompetence should not receive live, attenuated vaccines (viral or bacterial), and may not receive the full benefit of inactivated vaccines.
In reference to lymphocytes, immunocompetence means that a B cell or T cell is mature and can recognize antigens and allow a person to mount an immune response.