Vaccination With RA 27/3 Rubella Vaccine

Abstract

Eighteen children who had been successfully immunized two years previously with RA 27/3 rubella virus vaccine (either subcutaneously or intranasally) were examined for persistence of antibodies and resistance to intranasal challenge with "wild" virus (Brown strain). Hemagglutination inhibition (HI), complement fixation (CF), and anti-θ precipitating antibodies showed marked stability with no significant decline in titer during the two-year period; the differential fluorescent antibody (FA) test indicated that all children possessed antibody with the vaccine FA marker at the time of challenge. On intranasal inoculation of wild virus, only two children experienced reinfection, as evidenced by fourfold rises in HI, CF, and precipitating antibodies. The results suggest that the immunity resulting from RA 27/3 vaccine closely resembles that which follows natural infection, as evidenced by the appearance and persistence of precipitating antibody and the significant resistance to reinfection two years following vaccination.