Only about half of infants born to HIV-infected mothers in some African countries receive a minimum preventive dose of the drug nevirapine to help reduce the risk of mother-to-child HIV transmission, according to a study in the July 21 issue of JAMA, a theme issue on HIV/AIDS.

Jeffrey S. A. Stringer, M.D., of the University of Alabama at Birmingham and the Centre for Infectious Disease Research in Zambia, Lusaka, Zambia, presented the findings of the study at a JAMA media briefing at the International AIDS conference in Vienna.

In 2001, the United Nations General Assembly set an ambitious goal of reducing the global spread of new pediatric human immunodeficiency virus (HIV) infections by 50 percent by 2010. "Such an effort would require not only new scientific discoveries, but also substantial policy work, mobilization of huge new resources, and large-scale implementation of services in some of the least-resourced health systems in the world. A number of antiretroviral interventions are now available to reduce the risk of mother-to-child HIV transmission and clear guidelines have been developed for their implementation and use," the authors write. They add that despite this tremendous international investment, worldwide implementation of actual mother-to-child HIV prevention services has been slow.

Dr. Stringer and colleagues conducted a study to estimate the coverage of existing services to prevent mother-to-child HIV transmission in the African countries of Cameroon, Cote d'Ivoire, South Africa and Zambia. The study included the collection between June 2007 and October 2008 of umbilical cord blood samples from 43 randomly-selected facilities providing delivery services. All sites used at least single-dose nevirapine to prevent mother-to-child HIV transmission and some sites used additional prophylaxis drugs. Nevirapine coverage for HIV-exposed infants in the sample was determined by measuring both maternal nevirapine ingestion (confirmed by testing for the drug in the cord blood at delivery) and infant nevirapine ingestion (confirmed by direct observation).

Of the collected and tested cord blood specimens, 3,324 of 27,893 were HIV seropositive (12 percent). Complete data for cord blood nevirapine results were available on 3,196 HIV-seropositive mother-infant pairs. The primary outcome of total coverage (both maternal and infant dosing) was achieved in 1,725 HIV-exposed infants, with adjusted analyses indicating an overall coverage estimate for the 4 countries of 51 percent. Total coverage rates varied substantially by country and by site, and maternal nonadherence (i.e., absence of nevirapine in the cord blood among women with documented dispensation of antenatal [before birth] nevirapine) was common.The authors also found that failed coverage of nevirapine-based services was significantly associated with: younger maternal age, fewer antenatal care visits, vaginal delivery, and lower infant birth weight. The authors write that this aspect of the research, "has immediate implications regarding counseling of younger mothers and confirms the general importance of repeat antenatal visits as part of good obstetrical care."

The study was also able to precisely quantify the critical path or "cascade" that each mother-infant pair must negotiate in order to achieve successful prevention of mother-to-child HIV transmission. This cascade "begins with the offering of an HIV test and proceeds through posttest counseling to drug adherence and beyond. Our findings indicate that programmatic failures are common along this path, and that each clinic faces its own mix of challenges in maximizing service coverage," the researchers write.

In November 2009, the World Health Organization revised their international guidelines to make more complex drug regimens to prevent mother-to-child HIV transmission the international standard. The authors write that "this is a critical move toward global pediatric AIDS control, yet it holds only half the key. The other half lies in service coverage. Even the most potent interventions to prevent mother-to-child HIV transmission will not protect those infants who do not receive them."