FIG. 2.

Subjects with unchanged bactericidal activity after immunization with acellular pertussis vaccine. Relative survival, or CFU after incubation in serum with 10% complement/CFU after incubation in serum without complement, of B. pertussis strain BP338 in the presence of various concentrations of pre- and postimmunization serum. Subject 32-60 is the individual with the lowest preimmunization bactericidal activity, and subject 26-47 is the individual with the highest preimmunization bactericidal activity.