Wikipedia
Vaccine-naive
Vaccine-naïve is a lack of immunity, or immunologic memory, to a disease because the person has not been vaccinated. There are a variety of reasons why a person may not have received a vaccination including contraindications due to preexisting medical conditions, lack of resources, previous vaccination failure, religious beliefs, personal beliefs, fear of side-effects, phobias to needles, lack of information, vaccine shortages, physician knowledge and beliefs, and social pressure.