August 30, 2023
Integrating antiretroviral treatment (ART) into pregnancy care for people living with HIV has significantly reduced the number of children who acquire the virus before or soon after birth. Now, new research out of Zambia and Malawi, in collaboration with UNC-Chapel Hill, suggests that incorporating robust prevention strategies into routine pregnancy care could lead to substantial reductions in the numbers of HIV-negative mothers who acquire HIV during pregnancy and the postpartum period.
HIV prevention during pregnancy and the postpartum period is a key part of public health strategies promoted by UNAIDS, the World Health Organization and other global health leaders. In sub-Saharan African countries, these HIV prevention efforts have often focused on reducing vertical transmission – passing the virus to an unborn child – through a strategy called Option B+, in which lifelong ART therapy is prescribed to pregnant people known to be living with HIV, regardless of viral load.
However, because HIV-negative individuals have a higher risk of HIV infection during pregnancy, programs aiming to reduce new maternal HIV infections can also have important benefits. Preventing these HIV infections not only benefits the pregnant person’s own health but also removes the possibility of downstream infections in their infants from vertical transmission. Maternal HIV risk can be reduced if routine pregnancy care helps a couple gain access to prevention strategies, including HIV testing, ART medication and pre-exposure prophylaxis (PrEP) therapy.
Results from the UNC-led study in Zambia and Malawi found that increasing one of these three prevention strategies by 20 percentage points led to a 10-11% decrease in maternal HIV infection. A 20-percentage-point increase in two strategies used jointly led to a 19-23% decrease in maternal HIV infection, and a 20-percentage-point increase in all three strategies combined led to a 29% decrease in maternal HIV infection.
“While tremendous gains have been made in preventing infant HIV infections with maternal ART, less attention has been paid to preventing new maternal HIV infections during pregnancy and breastfeeding,” said Kimberly Powers, PhD, who is co-author on the study and associate professor of epidemiology at the UNC Gillings School of Global Public Health. “Since this is a period of heightened HIV risk, prevention efforts anchored in antenatal care can protect both pregnant patients and their babies.”
The study, published recently in the Journal of the International AIDS Society, was a collaboration between UNC’s Gillings School of Global Public and School of Medicine, the School of Public Health at the University of Zambia, the Ministries of Health in Zambia and Malawi, and the Yale School of Public Health. Using available population and public health data from Zambia and Malawi, the researchers created a model that estimated reductions in new maternal HIV infections that could be achieved with increases in three prevention strategies at or soon after beginning pregnancy care:
- HIV testing of male partners, resulting in HIV diagnosis and less condomless sex among those with previously undiagnosed HIV;
- Initiation (or re-initiation) of suppressive ART for male partners with diagnosed but unsuppressed HIV; and
- PrEP for HIV-negative female ANC patients with male partners known to be living with HIV or whose HIV status was unknown.
“Mathematical models allow us to combine biological and behavioral information about infectious disease transmission to make predictions about what we might see in a range of different scenarios,” Powers explained. “In this study, we developed a modeling framework with data from Malawi and Zambia to estimate HIV transmission events within couples so we could then assess the potential impact of HIV prevention strategies initiated during antenatal care in that context.”
In examining how integration of these strategies into antenatal care could lead to fewer new cases of HIV during pregnancy and the postpartum period, the researchers found that combined strategies which achieved 95% male testing, 90% male ART initiation/re-initiation and 40% female PrEP use reduced new maternal HIV infections by 45%.
“If these target uptake levels can be achieved, our analyses suggest that combining these prevention strategies could avert more than 50,000 of the estimated 120,000 maternal HIV infections acquired in sub-Saharan Africa each year,” Powers said. “Even at lower levels of uptake, our results suggest that focused HIV prevention interventions radiating from antenatal care could have substantial benefits for mothers – and, in turn, their babies. And while these analyses do not specify the exact manner in which these prevention strategies should be implemented, they suggest that efforts to identify optimal implementation approaches could lead to meaningful reductions in the HIV burden in these settings.”
The researchers chose to focus on Malawi and Zambia due to the high incidence of HIV in these areas and ongoing UNC collaborations with antenatal care practitioners, patients and their partners related to HIV prevention and research in these countries. While the results are specific to these two countries, the research team believes that they could be applied more broadly to other eastern and southern African countries with similar patterns of sexual behavior, HIV status awareness, viral suppression and use of pregnancy care.
Powers says that the research team is looking at ways to adapt their modeling framework and collect additional data to answer more granular questions about potential HIV prevention strategies in these settings.
“These additional analyses will allow us to more closely consider angles such as intervention timing and to fine-tune our recommendations for public health action,” she added.
Researchers on the study included Kimberly Powers, PhD, associate professor of epidemiology at the Gillings School; Wilbroad Mutale, PhD, professor at the University of Zambia School of Public Health; Nora Rosenberg, PhD, associate professor of health behavior at the Gillings School; Lauren Graybill and Katie Mollan, doctoral students in epidemiology at the Gillings School; Kellie Freeborn, PhD, postdoctoral fellow at the UNC Division of Global Women’s Health; Friday Saidi, PhD, postdoctoral fellow with the UNC Project Malawi; Suzanne Maman, PhD, professor of health behavior and associate dean for global health at the Gilllings School; Priscilla Lumano Mulenga, MSc, at the Zambia Ministry of Health; Andreas Jahn, PhD, and Rose K. Nyirenda, PhD, at the Malawi Ministry of Health; Jeffrey Stringer, MD, professor and director of the UNC Division of Global Women’s Health; Sten H. Vermund, MD, PhD, professor at the Yale School of Public Health; and Benjamin Chi, MD, professor of obstetrics and gynecology at the UNC School of Medicine.
Contact the UNC Gillings School of Global Public Health communications team at email@example.com.