To compare measles seroconversion rates (development of antibodies) at 13 months of age in HIV-infected and uninfected children on one of two immunization schedules: attenuated measles/mumps/rubella virus (M-M-R II) vaccine at 12 months versus attenuated measles vaccine (Attenuvax) at 6 months plus M-M-R II vaccine at 12 months.

Recommendations for the age at vaccination should balance the need to minimize the risk of morbidity and mortality with the benefit of achieving the highest seroconversion rates. Immunizing a more intact immune system at an earlier stage of HIV infection may in turn achieve better and long-lasting measles protection. This study will help define a more effective measles vaccine regimen for children diagnosed with HIV infection and will provide greater insight into the functional status of the HIV-infected children's humoral immune system.

Recommendations for the age at vaccination should balance the need to minimize the risk of morbidity and mortality with the benefit of achieving the highest seroconversion rates. Immunizing a more intact immune system at an earlier stage of HIV infection may in turn achieve better and long-lasting measles protection. This study will help define a more effective measles vaccine regimen for children diagnosed with HIV infection and will provide greater insight into the functional status of the HIV-infected children's humoral immune system.

Patients, HIV infected and uninfected, are randomized to one of two attenuated measles vaccine schedules: at 6 and 12 months of age, or at 12 months of age only. Attenuvax is administered as the month 6 vaccine and M-M-R II as the month 12 vaccine. Patients are followed for 24 months after the last vaccination.

Inclusion Criteria

Patients must have:

• Willing to have and receive results of HIV test
• Been born to mothers with HIV infection or history of AIDS-defining condition by CDC criteria.
• No history of opportunistic infection.
• No known exposure to measles within 14 days prior to study entry.
• CD4+ lymphocyte count >= 750 cells/mm3 or more than 15% at 6 months of age.
• Parent or legal guardian available to give written informed consent and be willing to comply with all study requirements.
• Childhood immunizations (other than measles) according to current recommendations of the Immunization Practice Advisory Committee and American Academy of Pediatrics.

NOTE:

• Coenrollment on other therapeutic protocols (except for ACTG 185) is permitted.

NOTE:

• Patients must be located in a geographical area where measles immunization at 12 months is standard of care.

Recommended:

• Childhood immunizations other than measles according to current guidelines.

Exclusion Criteria

Co-existing Condition:

Patients with the following symptoms or conditions are excluded:

• Intercurrent illness and/or fever for 7 days.
• Known sensitivity or allergy to neomycin or eggs.

Concurrent Medication:

Excluded:

• IVIG.
• Uninterrupted or anticipated steroid therapy (>= 2 mg/kg/day) for more than 2 weeks duration.

Patients with the prior condition are excluded:

• Platelet count < 50,000/mm3 at any time prior to study entry.

Prior Medication:

Excluded:

• Any IgG preparation within the past 6 months.