Population-based evaluations of programs for prevention of mother-to-child HIV transmission (PMTCT) are scarce. We measured PMTCT service coverage, regimen use, and HIV-free survival among children ≤24 mo of age in Cameroon, Côte D'Ivoire, South Africa, and Zambia.
Methods and Findings
We randomly sampled households in 26 communities and offered participation if a child had been born to a woman living there during the prior 24 mo. We tested consenting mothers with rapid HIV antibody tests and tested the children of seropositive mothers with HIV DNA PCR or rapid antibody tests. Our primary outcome was 24-mo HIV-free survival, estimated with survival analysis. In an individual-level analysis, we evaluated the effectiveness of various PMTCT regimens. In a community-level analysis, we evaluated the relationship between HIV-free survival and community PMTCT coverage (the proportion of HIV-exposed infants in each community that received any PMTCT intervention during gestation or breastfeeding). We also compared our community coverage results to those of a contemporaneous study conducted in the facilities serving each sampled community. Of 7,985 surveyed children under 2 y of age, 1,014 (12.7%) were HIV-exposed. Of these, 110 (10.9%) were HIV-infected, 851 (83.9%) were HIV-uninfected, and 53 (5.2%) were dead. HIV-free survival at 24 mo of age among all HIV-exposed children was 79.7% (95% CI: 76.4, 82.6) overall, with the following country-level estimates: Cameroon (72.6%; 95% CI: 62.3, 80.5), South Africa (77.7%; 95% CI: 72.5, 82.1), Zambia (83.1%; 95% CI: 78.4, 86.8), and Côte D'Ivoire (84.4%; 95% CI: 70.0, 92.2). In adjusted analyses, the risk of death or HIV infection was non-significantly lower in children whose mothers received a more complex regimen of either two or three antiretroviral drugs compared to those receiving no prophylaxis (adjusted hazard ratio: 0.60; 95% CI: 0.34, 1.06). Risk of death was not different for children whose mothers received a more complex regimen compared to those given single-dose nevirapine (adjusted hazard ratio: 0.88; 95% CI: 0.45, 1.72). Community PMTCT coverage was highest in Cameroon, where 75 of 114 HIV-exposed infants met criteria for coverage (66%; 95% CI: 56, 74), followed by Zambia (219 of 444, 49%; 95% CI: 45, 54), then South Africa (152 of 365, 42%; 95% CI: 37, 47), and then Côte D'Ivoire (3 of 53, 5.7%; 95% CI: 1.2, 16). In a cluster-level analysis, community PMTCT coverage was highly correlated with facility PMTCT coverage (Pearson's r = 0.85), and moderately correlated with 24-mo HIV-free survival (Pearson's r = 0.29). In 14 of 16 instances where both the facility and community samples were large enough for comparison, the facility-based coverage measure exceeded that observed in the community.
HIV-free survival can be estimated with community surveys and should be incorporated into ongoing country monitoring. Facility-based coverage measures correlate with those derived from community sampling, but may overestimate population coverage. The more complex regimens recommended by the World Health Organization seem to have measurable public health benefit at the population level, but power was limited and additional field validation is needed.
Please see later in the article for the Editors' Summary
For a pregnant woman who is HIV-positive, the discrepancy across the world in outlook for mother and child is stark. Mother-to-child transmission of HIV during pregnancy is now less than 1% in many high-income settings, but occurs much more often in low-income countries. Three interventions have a major impact on transmission of HIV to the baby: antiretroviral drugs, mode of delivery, and type of infant feeding. The latter two are complex, as the interventions commonly used in high-income countries (cesarean section if the maternal viral load is high; exclusive formula feeding) have their own risks in low-income settings. Minimizing the risks of transmitting HIV through effective drug regimes therefore becomes particularly important. Monitoring progress on reducing the incidence of mother-to-child HIV transmission is essential, but not always easy to achieve.
Why Was This Study Done?
A research group led by Stringer and colleagues recently reported a study from four countries in Africa: Cameroon, Côte D'Ivoire, South Africa, and Zambia. The study showed that even in the health facility setting (e.g., hospitals and clinics), only half of infants whose mothers were HIV-positive received the minimum recommended drug treatment (one dose of nevirapine during labor) to prevent HIV transmission. Across the population of these countries, it is possible that fewer receive antiretroviral drugs, as the study did not include women who did not access health facilities. Therefore, the next stage of the study by this research group, reported here, involved going into the communities around these health facilities to find out how many infants under two years old had been exposed to HIV, whether they had received drugs to prevent transmission, and what proportion were alive and not infected with HIV at two years old.
What Did the Researchers Do and Find?
The researchers tested all consenting women who had delivered a baby in the last two years in the surrounding communities. If the mother was found to be HIV-positive, then the infant was also tested for HIV. The researchers then calculated how many of the infants would be alive at two years and free of HIV infection.
Most mothers (78%) agreed to testing for themselves and their infants. There were 7,985 children under two years of age in this study, of whom 13% had been born to an HIV-positive mother. Less than half (46%) of the HIV-positive mothers had received any drugs to prevent HIV transmission. Of the children with HIV-positive mothers, 11% were HIV-infected, 84% were not infected with HIV, and 5% had died. Overall, the researchers estimated that around 80% of these children would be alive at two years without HIV infection. This proportion differed non-significantly between the four countries (ranging from 73% to 84%). The researchers found higher rates of infant survival than they had expected and knew that they might have missed some infant deaths (e.g., if households with infant deaths were less likely to take part in the study).
The researchers found that their estimates of the proportion of HIV-positive mothers who received drugs to prevent transmission were fairly similar between their previous study, looking at health facilities, and this study of the surrounding communities. However, in 14 out of 16 comparisons, the estimate from the community was lower than that from the facility.
What Do These Findings Mean?
This study shows that it would be possible to estimate how many infants are surviving free of HIV infection using a study based in the community, and that these estimates may be more accurate than those for studies based in health facilities. There are still a large proportion of HIV-positive mothers who are not receiving drugs to prevent transmission to the baby. The authors suggest that using two or three drugs to prevent HIV may help to reduce transmission.
There are already community surveys conducted in many low-income countries, but they have not included routine infant testing for HIV. It is now essential that organizations providing drugs, money, and infrastructure in this field consider more accurate means of monitoring incidence of HIV transmission from mother to infant, particularly at the community level.
Please access these websites via the online version of this summary at http://dx.doi.org/10.1371/journal.pmed.1001424.
The World Health Organization has more information on mother-to-child transmission of HIV
The United Nations Children's Fund has more information on the status of national PMTCT responses in the most affected countries