EVALUATION OF THE PROTECTIVE EFFICACY OF THE KILLED COCCIDIOIDES-IMMITIS SPHERULE VACCINE IN HUMANS

A vaccine consisting of formaldehyde-killed spherules of Coccidioides immitis, previously shown to provide protection against development of lethal coccidioidomycosis in laboratory animals, was evaluated in hum ans. This double blind ''Phase 3'' study, conducted during the period 1980 to 1985, involved 2,867 healthy subjects with no history of cocci dioidomycosis and negative skin tests. Randomized into vaccine (n = 1, 436) or placebo (n = 1,431) groups, the former received three intramus cular injections of 1.75 mg (dry weight) of spherules, the latter rece ived three injections of sterile 0.85% NaCl solution. Compatible clini cal presentation with cultural or serologic findings permitted detecti on of coccidioidomycosis. Of those receiving vaccine, nine developed c occidioidomycosis and nine additional were suspected of having the dis ease. Of the group receiving placebo, 12 developed coccidioidomycosis, and 13 additional were suspected of having the disease. All cases and suspected cases were mild. Under the conditions of this study, a slig ht but statistically insignificant reduction in the incidence of cocci dioidomycosis was noted in the vaccinated group compared with that in the placebo group, and there was no discernible difference in severity of disease between these groups.