Abstract
Summary
Thirty-five people, aged 18 to 56, whose prevaccination sera were without any antiviral effect on Japanese B encephalitis virus, received 2 doses, 2 cc each, 3 days apart, of a fluid, uncentrifuged, formalinized vaccine with a 50% immunogenic dose for mice of about 0.005 cc. Two weeks after the first dose of vaccine, 43% had antibodies with intracerebral neutralization indexes of 50 to 1,000, and 54% were positive if the equivocal indexes of 10 or more are included. The incidence of antibody development appeared to be higher among the younger adults (18 to 35 years) than among the older ones (36 to 56 years) but this requires confirmation. Neutralization of the formalin with NaHSOs immediately before injection of the vaccine had no effect on the development of antibodies.
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