A drug called nevirapine has been shown to be effective in reducing the risk of transmission of HIV at birth, but combination therapy of nevirapine and zidovudine does not improve outcomes, according to a study published in the current HIV/AIDS Journal of the American Medical Association.
Taha E. Taha, M.B.B.S., Ph.D., of the Bloomberg School of Public Health, The Johns Hopkins University, Baltimore, presented the findings of the study at the International AIDS Conference in Bangkok, Thailand.
Background information suggests that pre-birth counseling and human immunodeficiency virus (HIV) testing are not universal in Africa; thus, women often present in labor with unknown HIV status without receiving the standard HIVNET 012 nevirapine (NVP) regimen (a single oral dose of NVP to the mother at the start of labor and to the infant within 72 hours of birth). Information on the efficacy of adding zidovudine (ZDV) to a standard regimen of NVP is limited. This information is needed because most women in sub-Saharan Africa do not receive pre-birth antiretroviral treatment.
The researchers hypothesized that in situations in which the mother is tested for HIV at the time of presentation for delivery, giving two short drug regimens to the infant at birth would be more effective in increasing viral suppression and thus reducing mother-to-child transmission of HIV than a single regimen.
Dr. Taha and colleagues conducted a randomized trial between April 1, 2000, and March 15, 2003 at six clinics in Blantyre, Malawi, Africa. The trial included all infants born to 894 women who were HIV positive, received NVP intrapartum (during labor and delivery), and had not previously received antiretroviral treatment. Infants were randomly assigned to NVP single oral dose (n=448) and NVP (same dose) plus ZDV (n=446) for a week. Infants were enrolled at birth, observed at 6- to- 8 week visits, and followed up through 3 to 18 months. The investigators established the HIV status of 90 percent of all infants at 6 to 8 weeks.
The researchers found that the overall transmission at 6 to 8 weeks was 14.1 percent in infants who received NVP alone and 16.3 percent in those who received NVP plus ZDV. Excluding infections at birth in the study, the risk of transmission at 6 to 8 weeks was similar for infants who received NVP only (6.5 percent) and those who received NVP plus ZDV (6.9 percent).
Almost all infants were breastfed at week 1 and 6 to 8 weeks. Adverse events were comparable in infants receiving NVP only and NVP plus ZDV.
"Our studies in Malawi suggest several possible options for prevention of HIV transmission in breastfed infants and in the context of the resource constraints of sub-Saharan Africa. First, voluntary counseling and testing should be available early during pregnancy (or even before pregnancy), allowing HIV-infected women and their infants to receive standard NVP prophylaxis (e.g., a woman could self-administer NVP when labor contractions commence). Our current study and other studies in Africa indicate that this regimen appears to be safe and effective. Second, women who present at the labor ward with unknown HIV status should be tested and offered a standard NVP regimen (for both mother and infant), if time is adequate to counsel, test for HIV, and give intrapartum NVP (if indicated). Third, women arriving too late to the labor ward to be counseled, tested for HIV, and treated intrapartum, should be tested postnatally, and if positive, their infants should be given postexposure prophylaxis," the researchers write.