Rose Wilcher, Root to Rise

Nicolette Naidoo, Wits RHI

CATALYST was built to answer a practical question: what does it take to deliver PrEP choice in the real world?

Implemented through the PEPFAR/USAID-supported MOSAIC project, CATALYST was a multi-country implementation study designed to assess an enhanced service delivery package offering multiple PrEP products to women across 28 public health sites in Kenya, Lesotho, South Africa, Uganda, and Zimbabwe. It was not just a study of products, but of delivery: how providers counsel for choice, how public sector clinics adapt, what drives women's choice of PrEP method and use over time, and what health systems need to sustainably support a multi-product PrEP market. Since the study began in May 2023, 3,970 women had enrolled in Stage I, which offered oral PrEP and the dapivirine ring, and 1,209 had enrolled in Stage II, which added injectable cabotegravir for PrEP (CAB PrEP).

Then, in January 2025, the study was prematurely shut down – one year earlier than planned – as part of the broader dismantling of U.S. foreign aid. Study teams across the five countries had to abruptly inform participants and facility staff of the closure, including the end of access to the ring and CAB PrEP through the study. Important data already collected on participant experience, provider perspectives, health system implementation, and community acceptability were left unanalyzed and unshared. 

Additional support has now been secured through Project Resource Optimization (PRO) to complete analysis and dissemination of those data, including sharing findings with participants, communities, and advisory bodies who never had the chance to hear the study’s results. In addition to supporting ethical study close-out, this funding creates an important opportunity to ensure that evidence generated through CATALYST can still inform current policy and program decisions.

Early Findings on PrEP Choice and Delivery

Even from Stage I, CATALYST produced important early findings. Across the five countries, women made different choices when offered oral PrEP or the dapivirine ring, with most choosing oral PrEP and a substantial minority choosing the ring. Reported reasons for product choice underscored that women value different features, including ease of use, effectiveness, and avoiding daily pill-taking. Early data also showed variation in return and discontinuation patterns by product, as well as some switching between methods over time. Together, these findings reinforce a central point: product choice matters, and different women are likely to prefer and use different prevention methods under real-world conditions.

Interim findings also suggested that expanding the PrEP market brought new and former users into the fold, increased overall PrEP coverage at participating sites, and was feasible across a range of delivery settings. Providers were generally positive about multi-method counseling for informed decision-making, and early Stage II data showed that when CAB PrEP was added to the method mix, it quickly became the most popular method, while oral PrEP and the ring still retained dedicated users.

CATALYST also began to generate practical evidence on what it takes to operationalize PrEP choice in public health systems. Early findings pointed to the importance of provider preparation, counseling approaches that support informed choice, and site-level adaptations to strengthen delivery of multiple methods. These are not product-specific lessons. They are implementation questions that remain highly relevant as countries continue to expand PrEP options.

Why CATALYST Still Matters for LEN Rollout

The PrEP landscape has shifted since CATALYST was shut down. In many African countries, interest in the ring and CAB PrEP is waning, although some countries will continue to offer them. At the same time, attention has turned sharply toward lenacapavir, or LEN. LEN was not part of CATALYST. But that does not lessen the study’s relevance. The most important lessons from CATALYST are not product-specific; they are about how to introduce and manage PrEP choice in routine health systems.

Although Stage II included only oral PrEP, the ring, and CAB PrEP, the study can still help answer questions that are directly relevant to countries preparing for or rolling out LEN. Many are facing familiar challenges: how to integrate a new product into existing services, support counseling across multiple methods, understand patterns of uptake and persistence, forecast demand, and translate policy commitments to choice into workable service delivery models.

CATALYST offers a valuable evidence base for those questions. Further analysis will help countries better understand patterns of use among specific populations, including adolescent girls and young women, pregnant and breastfeeding women, and key populations. It can provide lessons on switching, continuation, side effects, and demand generation. It can also inform broader planning for differentiated service delivery, supply dynamics, and the design of adaptive and scalable multi-product PrEP programs.

As Professor Saiqa Mullick, Director of Implementation Science at Wits RHI and lead partner on the project said, “Although CATALYST ended far earlier than planned, this award makes it possible to analyze and disseminate critical implementation data, support ethical close-out with participants and communities, and translate the study’s lessons into decisions that matter for current and future PrEP programs.” 

LEN is changing prevention options, but its introduction does not start from zero. Countries need evidence not only on the product itself, but on how health systems deliver choice effectively when new methods are added. CATALYST was designed to study exactly that. Completing the analysis of these data will help ensure that the evidence generated and implementation experience captured through the study can still be used to support LEN rollout and future PrEP product introductions.