Skin reactivity and antibody response following vaccination against smallpox.

Abstract Revaccination between 2 and 5 years after the last vaccination induced higher complement-fixation titres than revaccination 7-63 years after the last vaccination. The highest CF titres were reached during the 3rd to the 5th week after vaccination. Fifty-two serum samples, taken 137 or more days after a successful vaccination, all showed CF titres lower than 1/2. In a group of successfully vaccinated persons with no post-vaccinal complications, 65 out of 66 had a successful `take' after one or two subsequent vaccinations. Sera of persons receiving primary vaccination showed significantly lower CF titres than sera of revaccinated persons. Cases of post-vaccinal encephalitis showed greater antibody response than uncomplicated successfully vaccinated cases in both the primary vaccination and revaccination groups. The antibody response in revaccinated persons with post-vaccinal encephalitis was greater than that in the group of successfully revaccinated cases without encephalitis. A group of 26 naturally hyporeactive persons completely failed to `take' even after vaccination repeated between 3 and 10 times (average 5 times per person). The frequency of seropositives in this group, and the height of their CF titres, were significantly lower than in the group of successfully vaccinated persons. These findings support the view that untreated persons who repeatedly fail to `take' with the vaccine must not be considered immune. In vaccinated persons treated with immunoglobulin (with or without simultaneous treatment with Marboran) antibody production was apparently diminished. Treatment of patients with Marboran significantly lowers the capacity of the vaccine to `take'.