hypervaccination

Repeated inoculation of an individual already immunized; used as a means of preparing a highly potent antiserum.

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hy·per·vac·ci·na·tion (hi″pər-vak″sĭ-naґshən) the subsequent inoculation (one or more times) of a previously immunized animal with enough vaccine to enable it to produce a serum protective to other animals.