OBJECTIVE: To study the immuno-persistence after inoculating with the domestic BRD II strain rubella vaccine among infants and young children. METHODS: Hemagglutination inhibition (HI) antibody detection method was used to test on children at age 6 to 18 months without rubella infection or rubella vaccine immunization in Yantai city of Shandong province and were selected for the observation of the immuno-persistence against the domestic BRD II strain rubella vaccine from 1995 to 1998. RESULTS: Positive rates of HI antibody among children of 6, 7, 8, 9, 12 and 18 month-old of inoculation were 94.44%, 97.22%, 96.67%, 100.00%, 100.00%, 100.00% and 93.10%, 93.55%, 96.77%, 96.97%, 100.00%, 100.00% (P > 0.05), in one or two years respectively. The geometric mean reverse titers (GMRTs) were about 50% lower than that after 1 month after 1 year. Similar results were found that after 2 years GMRTs was about 50% lower than that after 1 year of inoculation. There was highly significant difference on GMRTs of HI antibody between infants with 6 to 7 month-olds (29.89) and young children with 8 to 18 month-olds (53.00) after 2 years of inoculation (t = 3.58, P < 0.001). CONCLUSION: The immunization schedule at the first dose for BRD II strain rubella vaccine should be started when the child is 8 month old. For the second dose, the immunization schedule used in other developed countries should be referred adopted in China.
OBJECTIVE: To study the immuno-persistence after inoculating with the domestic BRD II strain rubella vaccine among infants and young children. METHODS: Hemagglutination inhibition (HI) antibody detection method was used to test on children at age 6 to 18 months without rubella infection or rubella vaccine immunization in Yantai city of Shandong province and were selected for the observation of the immuno-persistence against the domestic BRD II strain rubella vaccine from 1995 to 1998. RESULTS: Positive rates of HI antibody among children of 6, 7, 8, 9, 12 and 18 month-old of inoculation were 94.44%, 97.22%, 96.67%, 100.00%, 100.00%, 100.00% and 93.10%, 93.55%, 96.77%, 96.97%, 100.00%, 100.00% (P > 0.05), in one or two years respectively. The geometric mean reverse titers (GMRTs) were about 50% lower than that after 1 month after 1 year. Similar results were found that after 2 years GMRTs was about 50% lower than that after 1 year of inoculation. There was highly significant difference on GMRTs of HI antibody between infants with 6 to 7 month-olds (29.89) and young children with 8 to 18 month-olds (53.00) after 2 years of inoculation (t = 3.58, P < 0.001). CONCLUSION: The immunization schedule at the first dose for BRD II strain rubella vaccine should be started when the child is 8 month old. For the second dose, the immunization schedule used in other developed countries should be referred adopted in China.