Response to experimental challenge in persons immunized with different rubella vaccines.

The response to experimental challenge with rubella virus was studied in 113 volunteers, ages 13 to 17 years, immunized with three rubella vaccines: HPV-77-DE-5 and Cendehill (inoculated subcutaneously) and RA-27/3 (administered subcutaneously to one group and intranasally to a second group). The occurrence of side effects ranged from 16% in the Cendehill vaccines to 32% in the RA-27/3-intranasal vaccinees. Antibody response to primary vaccination as measured by CF was significantly lower in the Cendehill vaccines. Challenge by intranasal instillation of RA-27/3 a year later produced no adverse effects. Serologic response was measured by testing for CF, HI, and neutralizing and sensitizing antibodies. Booster response, a fourfold increase in antibody fiter after challenge as evidenced by at least one of the tests, occurred in 67% of the Cendehill vaccinees, in 47% of HPV-77 vaccines, and in only 7 to 11% of RA-27/3 vaccinees. Of 37 subjects exhibiting booster response, 27 had an increase in antibody titer demonstrated by two or more serologic tests; 16 of these 27 were Cendehill vaccinees. These results confirm our previous observations and that of others that the RA-27/3 rubella vaccine has the highest immunogenic potential.