Complement Fixing Antibody Response of Man to Yolk Sac-Grown Rocky Mountain Spotted Fever Vaccine∗

Summary and ConclusionsThe spotted fever group complement fixing antibody response was used as a measure of the immunogenicity of a commercially available killed Rocky Mountain spotted fever vaccine in human subjects. A single-dose primary course of vaccine elicited a detectable antibody response in only about 22% of 68 subjects, whereas a 3-dose primary course stimulated the development of complement fixing antibodies in about 63% of eight subjects. The low antibody titers attained may be a function of the relatively low complement fixing antigen content of the vaccine.A booster dose of vaccine given between 1 and 6 months after the primary course failed to elicit an antibody response in the majority of subjects. A second booster dose, given a year after the 6-month booster dose, also failed to cause a significant response. On the other hand, three subjects who had last received RMSF vaccine several years prior to this study developed a typical secondary antibody response upon revaccination. These same s...