Rubella immunization in human immunodeficiency virus type 1-infected children

Background: HIV infection can have important although sometimes unexpected consequences, such as contributing to enlargement of the pool of rubella-susceptible children. Methods: At the Federal University of Sao Paulo, Brazil, we assessed response to rubella immunization at 15 months of age in 15 human immunodeficiency virus type 1 (HIV)-infected children, 20 seroreverted children (SR) and 18 healthy control children born to HIV-seronegative mothers (CON). Blood samples were collected before and 3 months after vaccination. All HIV-infected children had started highly active antiretroviral therapy during their first 6 months of life. Serum samples were tested with a rubella IgG enzyme-linked immunosorbent assay kit. Results: HIV children in immunologic categories 2/3 had lower rubella antibody titers (geometric mean, 33 IU/mL) than those from CON (125 IU/mL) and SR group (236 IU/mL) (Tukey, P = 0.01). Antibody values after vaccination were positively associated with CD4 T cell numbers and negatively associated with HIV viral load assessed immediately before vaccination. The percentage of children with protective antibodies after vaccination (above 10.0 IU/mL) was also significantly different among groups (Fisher's exact test, P = 0.013): CON, 94%; SR, 100%; HIV category 1, 100%; HIV category 2/3, 62%. Conclusions: HIV-infected children with a preserved immune system at measles-mumps-rubella immunization can have a good response to rubella vaccine. In contrast, those in more advanced categories for HIV infection respond poorly.