Which of the following is NOT an option for immunization?

Gene therapy vaccines are not considered a traditional option for immunization in the same sense as live attenuated, inactivated, or subunit vaccines. Immunization typically refers to the administration of vaccines to produce immunity against specific diseases. The three other types—live attenuated vaccines, inactivated vaccines, and subunit vaccines—are all established methods used to stimulate an immune response.

Live attenuated vaccines contain weakened forms of the pathogen that can safely replicate in the body, thereby eliciting a strong immune response without causing disease. Inactivated vaccines consist of pathogens that have been killed or inactivated, so they cannot replicate but still provoke an immune response. Subunit vaccines include only pieces (subunits) of the pathogen, which can also effectively stimulate an immune response without containing any live components.

Gene therapy vaccines, in contrast, are more experimental and involve introducing genetic material into the body, which instructs cells to produce proteins that resemble components of the pathogen. While this approach is part of emerging research in vaccine technology and may lead to new types of immunization strategies, it currently does not fall under the conventional categories of vaccines traditionally used for immunization against infectious diseases.