Every year, nearly 6 million children under the age of five die because of an infectious disease. A particularly vulnerable group is HIV-negative babies born to HIV-infected mothers. Even though they are not infected with the virus themselves, these babies are four times more likely than non-HIV exposed babies to die before their first birthday, mainly due to infections such as meningitis and pneumonia.
New research may help explain why these babies are so prone to infection: they have unusually low levels of infection-fighting blood proteins (antibodies), which protect against infection by directing immune cells to attack and destroy pathogens. Mothers transfer antibodies to their child through the placenta late in pregnancy.
Researchers at Imperial College London and Stellenbosch University in South Africa measured the antibody levels of 109 HIV-infected and uninfected mothers in a community health centre in Khayelitsha, a growing urban settlement in South Africa. They also measured the antibody levels of their babies. At birth, the babies born to infected mothers had significantly lower levels of antibodies against many bacterial infections, including meningitis, whooping cough, pneumonia, and tetanus.
Better immunization strategies could help
To see how well these babies responded to vaccination, researchers measured their antibody levels at four months of age, after their routine shots. Even though they had low antibody levels at birth, the babies in the study responded well to vaccines: compared with the babies in the control group, they produced similar levels of antibody to some vaccines and higher levels to others. This may lead to designing better vaccine strategies to help protect vulnerable babies, either by vaccinating the babies earlier or by vaccinating pregnant mothers.
“Targeted vaccination strategies may be required in HIV-infected women and their infants,” write the authors in their paper, published in the February issue of the Journal of the American Medical Association (JAMA).
Intervention programs in parts of developing countries, including Africa, have helped lower mother-to-child transmission of HIV to about 5%, down from 20% to 30%.
For more information, please see HIV and Pregnancy and HIV and Your Child in the Health A to Z section.