Reasons Complicating the Development of Vaccines to Combat Chronic Diseases

Multiple Choice

Reasons complicating the development of vaccines to combat chronic diseases include _____.(Select all that apply.)

A) evasion of the host's immune system by the pathogen
B) the polymorphic diversity of MHC class I and class II molecules
C) the generation of inappropriate immune responses that do not eradicate the pathogen
D) survival of the infectious agent for long periods inside the host
E) high mutation rates in the pathogen.