News-Letter

In an attempt to quell the AIDS epidemic in Africa, scientists at Makerere University in Uganda have begun working with scientists from Hopkins to test a promising new AIDS vaccine for children.

The clinical trials testing out the new vaccine, known as ALVAC-HIV, are a public health landmark. They represent the first clinical safety trial in Africa of a vaccine to prevent mother-to-child transmission of HIV through breast feeding.

Mother-to-child transmission, or MTCT, is common in Africa. Each year, more than 700,000 children worldwide are infected with HIV by their parents. About 90 percent of these MTCT infections occur in Africa. Some 15-20 percent are infected during pregnancy, with 50 percent of infections occurring during delivery and 33 percent through breast feeding, according to published studies from UNICEF.

In order to be infected with HIV, blood or bodily fluid containing HIV from an infected person must come into contact with the blood of another individual. The mucous membranes of the body are a primary route for the virus to enter the bloodstream in humans. Transmission of the virus from the mother to the child can occur in the uterus during the last weeks of pregnancy or at childbirth.

Though MTCT through breast feeding represents a high risk, there is recent evidence supporting the practice. In a study published in the April 29, 2005 issue of AIDS, officials at the Bloomberg School of Public Health and the University of Zimbabwe found that exclusive breast feeding substantially reduced the transmission of HIV from mother to infant and infant death, as compared with partial breast feeding.

The milk produced by mothers is high in an antibody called immunoglobulin IgA. A newborn is protected against many gut illnesses that can cause diarrhea or widespread infection.

In the study, infants that were introduced to solid foods or animal milk within the first three months after birth were at a four times more likely to contract HIV through breast feeding.

Current recommendations from the World Health Organization state that, when replacement feeding is possible, HIV-infected mothers should avoid breast feeding their infant. Otherwise, exclusive breast feeding is recommended.

The Ugandan-led study will recruit 50 infants born to HIV-positive mothers in the capital city of Kampala. Previous research using the vaccine in Ugandan adults showed it to be safe.

Current trials in adults of the ALVAC-HIV vaccine in Thailand are presently being funded by the Thai and U.S. governments. The study is determining the effectiveness of a combination vaccine of ALVAC-HIV with AIDSVAX-B/E in 16,000 participants with no history of HIV infection.

If the Kampala clinical trials prove effective in reducing the chance of infants becoming infected during breast feeding, researchers estimate that the ALVAC-HIV vaccine could prevent 50 percent of Ugandan child AIDS cases. Nearly 22,000 children in Uganda are infected with HIV each year. The study is expected to near completion in mid-2007. 

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