Providing long-acting (LA) antiretroviral therapy (ART) to breastfeeding women with HIV who struggle with adherence may be a cost-effective way to prevent infant HIV infections in Zimbabwe, according to a modeling analysis.
Switching from the current standard of care (SoC) to LA-ART could prevent approximately 160 infant HIV infections per year while also saving money. In 2023, an estimated 60,000 infants worldwide acquired HIV through breastfeeding, yet the risk of transmission drops to less than 1% when the mother is on effective ART. Zimbabwe reports around 1,800 new infant infections annually during breastfeeding. Pregnant women in Zimbabwe currently receive oral tenofovir/lamivudine/dolutegravir (TLD) but transitioning to cabotegravir/rilpivirine (CAB/RPV) at delivery could help those struggling with adherence. However, LA-ART is not yet available in Zimbabwe, and the possibility of an affordable generic formulation remains uncertain.
CAB/RPV has not been studied in pregnancy, and there is limited data on its effectiveness in this population. The analysis aimed to determine the cost point at which this intervention would be beneficial. Using the Cost-Effectiveness of Preventing AIDS Complications (CEPAC) model, researchers simulated costs for two groups of pregnant women with adherence challenges: those who were virally suppressed at delivery and those who were not. The two strategies modeled were continuing the current SoC with TLD or switching from TLD to CAB/RPV.
The outcomes included vertical transmission rates, pediatric life expectancy, and total costs, which encompassed drug expenses during breastfeeding and pediatric HIV-related lifetime care costs. The study defined an incremental cost-effectiveness ratio (ICER) of less than $800 per year of life saved as “cost-effective,” equivalent to 0.5 times Zimbabwe’s GDP per capita.
Based on clinical trial data, the SoC with TLD, which costs $43.20 per person annually, led to 63% of nonvirally suppressed mothers and 78% of virally suppressed mothers achieving viral suppression at six months. Meanwhile, LA-ART with CAB/RPV, which costs $144 per person annually, increased viral suppression rates to 85% in nonvirally suppressed and 90% in virally suppressed mothers.
The estimated vertical transmission rates ranged from 0.6% to 0.89% per month over 18 months of breastfeeding, assuming 70% of virally suppressed and 79% of nonvirally suppressed mothers remained engaged in care for 24 months. For women not virally suppressed at delivery, the postpartum vertical transmission rate was estimated at 4.38%, with a total vertical transmission rate of 7.49%. Switching to LA-ART reduced the total transmission rate to 6.58%, preventing 66 infant infections annually, increasing infant life expectancy from 66.08 to 66.40 years, and slightly reducing costs from $764 to $763 per year.
For virally suppressed women, the SoC resulted in a 2.72% postpartum vertical transmission rate and a 4.17% total vertical transmission rate. Switching to LA-ART reduced total vertical transmission to 3.8%, preventing 97 infant infections annually and slightly extending life expectancy from 67.40 to 67.52 years, though costs increased from $444 to $554 per year.
The study based its projections on data from 31,388 infants born in Zimbabwe in 2023 to mothers with HIV, including 7,211 whose mothers were not virally suppressed at delivery and 24,177 whose mothers were virally suppressed.
The effectiveness of ART in preventing transmission is well established, and while LA-ART may be preferable in certain cases, similar outcomes can be achieved through other means if LA-ART is not affordable. However, for women who have yet to achieve viral suppression, LA-ART could be particularly beneficial.
If CAB/RPV were 5% more effective than the base-case assumptions, it could prevent 215 infant infections annually, while an 8% higher efficacy could avert 250 cases. If LA-ART also reduced postpartum care disengagement by 75%, the number of averted infections could rise to 450 per year. However, LA-ART would cease to be cost-effective for women not virally suppressed at delivery if the cost of CAB/RPV exceeded $276 per year or if six-month suppression rates fell below 68%.
For women already virally suppressed at delivery, LA-ART improved projected pediatric life expectancy but at a higher cost, making it less cost-effective under base-case assumptions. CAB/RPV would need to cost $84 per year or less for LA-ART to be considered cost-effective in this group.
These findings suggest that postpartum women should be prioritized for access to LA-ART. Future research should include postpartum women and explore ways to make these medications affordable in the communities that need them most.
