Long-Acting ART Could Prevent More Infant HIV Infections in Zimbabwe

SAN FRANCISCO — Providing long-acting (LA) antiretroviral therapy (ART) to breastfeeding women with HIV who face adherence challenges may be a cost-effective way to prevent infant HIV infections in Zimbabwe, according to a modeling analysis.

Using LA-ART instead of the current standard of care (SoC) averted approximately 160 infant HIV infections a year while saving money, Sujata Tewari, of Massachusetts General Hospital in Boston, reported in a poster at the 2025 Conference on Retroviruses and Opportunistic Infections (CROI).

“In 2023, an estimated 60,000 infants acquired HIV through breastfeeding, [but] the risk of an infant acquiring HIV through breastfeeding drops dramatically to less than 1% if the mother is on effective antiretroviral treatment,” Tewari said during a CROI press conference.

Around 1,800 new infant infections occur during breastfeeding in Zimbabwe each year, Tewari said. Pregnant women in Zimbabwe currently receive oral tenofovir/lamivudine/dolutegravir (TLD) in pregnancy, but switching to cabotegravir/rilpivirine (CAB/RPV) at delivery may reduce barriers for those struggling with adherence, she said. LA-ART is not presently available in Zimbabwe, and it’s unclear whether a more affordable generic formulation will become available in low-resource settings.

Additionally, “CAB/RPV has not been studied in pregnancy, nor is there data of its effectiveness in this population,” Joseph Cherabie, MD, of the Washington University School of Medicine in St. Louis, told MedPage Today. “They are trying to specify the cost point at which this would prove beneficial in their population, which is them trying to say, ‘This will work if it is at the right cost for us,'” added Cherabie, who was not involved in the study.

The researchers used the Cost-Effectiveness of Preventing AIDS Complications (CEPAC) model to simulate costs in two cohorts of women who were engaged in prenatal care and faced adherence challenges with TLD ART in pregnancy: women virally suppressed at delivery and women not virally suppressed at delivery. The two strategies modeled were maintaining the SoC with continuation of TLD and switching from TLD to CAB/RPV.

The outcomes modeled included vertical transmission, pediatric life expectancy, and total costs, defined as material drug costs during breastfeeding plus pediatric HIV-related lifetime care costs. The researchers defined an incremental cost-effectiveness ratio (ICER) of less than $800/year of life saved as “cost-effective,” which is equivalent to 0.5 times Zimbabwe’s gross domestic product (GDP).

In the model, based on data from clinical trials, the researchers estimated that the SoC, with TLD costing an annual $43.20 per person, would result in 63% of nonvirally suppressed mothers and 78% of virally suppressed mothers achieving 6-month suppression. LA/ART with CAB/RPV, meanwhile, would result in 85% of nonvirally suppressed and 90% of virally suppressed mothers achieving 6- month suppression, with annual drug costs of $144 per person.

The researchers estimated the likely rates of vertical transmission as 0.6% to 0.89% per month with 18 months of breastfeeding when 70% of virally suppressed and 79% of nonvirally suppressed women remained engaged in care for 24 months.

Assuming a postpartum vertical transmission rate of 4.38% and a total vertical transmission rate of 7.49% in women not virally suppressed at delivery, switching to LA-ART would result in a total vertical transmission rate of 6.58%, thereby averting 66 annual infant infections, increasing infant life expectancy from 66.08 to 66.40 years, and costing $763/year instead of $764/year.

In women virally suppressed at delivery, assuming the SoC would result in 2.72% postpartum vertical transmission and 4.17% total vertical transmission, switching to LA-ART would lower total vertical transmission to 3.8%, averting 97 annual infant infections and extending infant life expectancy from 67.40 to 67.52 years, but costing $554/year instead of $444/year.

These models’ assumptions relied on data from 31,388 infants born in Zimbabwe to mothers with HIV in 2023, including 7,211 who were not virally suppressed at delivery and 24,177 who were virally suppressed at delivery.

“I think the message here is that U=U [undetectable=untransmittable] is so effective and they are able to achieve that at low cost with other regimens,” Cherabie said. LA-ART is preferable if it works and is affordable; “otherwise we can obtain these results in other ways,” Cherabie said. “Still, LA-ART is very helpful in cases where viral suppression isn’t yet obtained, and that’s where the goal for it being utilized best lies.”

If CAB/RPV efficacy is 5% more effective than their base-case assumptions, switching to it would prevent an estimated 215 infant infections a year. At 8% higher efficacy, it would avert 250 annual infant infections. If use of LA-ART also reduced postpartum care disengagement by 75%, the number of averted infant infections rises to approximately 450 per year.

LA-ART would no longer be cost effective for women not virally suppressed at delivery if the cost of CAB/RPV exceeded $276 per year or if the 6-month suppression fell below 68%.

“For women virally suppressed at delivery, LA-ART led to higher projected pediatric life expectancy than standard of care, but total costs were higher, and LA-ART would not be cost-effective with base-case assumptions,” Tewari reported. CAB/RPV would need to cost $84/year or less for LA-ART to become cost effective for women virally suppressed at delivery.

“These findings indicate that postpartum women should be a priority group for access to long-acting ART,” Tewari said. “Studies of long-acting formulations should include postpartum women, and they should include agreements for these medications to be made at a low cost for the communities who stand to benefit the most from them.”

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