Projected long-term impacts of US funding cuts on TB and HIV in South Africa and the TB Programme response

Mathematical modeling projects that unmitigated US funding cuts for TB and HIV programs in South Africa between 2025 and 2035 could reverse years of progress by causing hundreds of thousands of additional infections and deaths, underscoring the urgent need for rapid domestic and programmatic responses to avert these catastrophic outcomes.

The Gist

Imagine South Africa's fight against Tuberculosis (TB) and HIV as a massive, complex garden that has been carefully tended for over a decade. Thanks to hard work and funding, the weeds (disease) were being pulled out, and the flowers (healthy people) were blooming. The garden was finally looking beautiful.

But in early 2025, a major water truck (the US government's funding) suddenly stopped delivering water. This paper is a warning from the gardeners (researchers) about what happens if the garden doesn't get enough water to survive.

Here is the story of that garden, broken down simply:

1. The Problem: The Water Truck Stops

For years, South Africa's garden relied on three main sources of water:

• Local Rain: Money from the South African government (67%).
• Global Neighbors: Money from the Global Fund (19%).
• The Big Truck: Money from the US (PEPFAR/USAID) (14%).

When the Big Truck stopped in 2025, the gardeners panicked. They knew that without that extra water, the plants would struggle. This report uses a crystal ball (mathematical model) to predict what the garden would look like over the next 10 years if they didn't find a way to replace that water.

2. The Prediction: A Storm is Coming

The researchers looked at two possible futures:

• The "Bad News" Scenario: The water shortage continues forever.
• The "Recovery" Scenario: The gardeners scramble to find new water, but it takes a few years to get back to normal.

What the crystal ball showed:

• The HIV Bushes: Without enough medicine (ART), the HIV "weeds" would spread wildly. Instead of just a few new infections, they predicted hundreds of thousands to a million new cases.
• The TB Vines: Because HIV weakens the body, it makes TB grow faster. If HIV gets worse, TB explodes.
  • The Numbers: They predicted an extra 220,000 to 730,000 people getting sick with TB, and 67,000 to 225,000 people dying from it between 2025 and 2035.
• The Long Tail: Even if they fixed the problem in 2029, it would take 8 to 12 more years to get the garden back to how it looked before the water truck stopped. It's like a car that hits a pothole; even after you fix the tire, it takes a long time to smooth out the ride.

3. The Gardeners' Response: The Emergency Hose

The South African National TB Programme (NTP) didn't just sit there. They grabbed a garden hose (emergency funding and action) to try to save the plants.

• The Big Push: They launched a campaign to test 5 million people for TB. In just one year, they tested 3.5 million. This was like spraying water on the wilting plants to keep them alive.
• New Money: The government found about $41.7 million in emergency funds to replace the lost US money. They gave most of it to HIV services, but it's still a bit unclear exactly how much is going specifically to the TB section of the garden.

4. The Big Lesson: Why This Matters

The paper is essentially saying: "We are doing our best, but the situation is still dangerous."

• The Domino Effect: You can't just fix one part of the garden. If you stop watering the HIV section, the TB section dies too. They are connected like vines on the same trellis.
• The Cost of Waiting: If we wait too long to fix the funding, the disease spreads so fast that it will take a decade to clean up. It's much cheaper and easier to keep the water flowing now than to try to replant the whole garden later.
• Hope: The "End TB" campaign shows that if everyone works together (political will, new technology, and money), we can save the garden. But we need to act fast.

The Bottom Line

Think of this report as a weather forecast for a storm that hasn't hit yet. The researchers are saying, "If we don't keep the funding flowing, the storm will wipe out years of hard work, and thousands more people will get sick or die."

The good news is that the South African gardeners are already trying to build their own water tanks (domestic funding) and are testing everyone they can. But they need the whole world to keep helping them pour water, or the garden might not survive the drought.

Technical Summary

Technical Summary: Projected Long-Term Impacts of US Funding Cuts on TB and HIV in South Africa

1. Problem Statement

South Africa faces a critical threat to its progress in combating Tuberculosis (TB) and HIV due to the withdrawal of United States government funding in early 2025. While the country has achieved significant reductions in TB incidence (30.4%) and mortality (47.7%) between 2009 and 2019, these gains are heavily reliant on external financing. In the 2024/25 fiscal year, external funding (Global Fund, USAID, PEPFAR) accounted for approximately 33% of the National TB Programme (NTP) budget and 14% of the HIV programme.

The core problem addressed is the potential catastrophic reversal of public health gains if these funding cuts are unmitigated. Specifically, the study investigates the long-term epidemiological consequences (2025–2035) of service disruptions in key areas: TB preventive therapy, testing/screening, treatment linkage, and Antiretroviral Therapy (ART) coverage.

2. Methodology

The authors employed the Thembisa TB/HIV mathematical model, a dynamic model that integrates TB programme interventions with HIV epidemic dynamics.

• Scenarios Modeled: The study utilized stakeholder-informed scenarios (derived from NTP consultations) to define minimum and maximum reduction ranges for specific interventions (Table 1).
  • TB Interventions: Reductions in Preventive Therapy (20–25%), Testing/Screening (20–25%), and Linkage to Treatment (15–25%).
  • HIV Interventions: Reductions in ART coverage (14–28%).
• Time Horizon: Projections cover the decade from 2025 to 2035.
• Comparative Scenarios:
  1. Unmitigated Disruption: Service reductions persist without recovery (2025–2035).
  2. Gradual Recovery: Service reductions occur from 2025–2028, with a gradual return to baseline levels starting in 2029 (coinciding with the end of the current US administration term).
• Data Triangulation: Model assumptions were cross-validated with expenditure data to ensure financial plausibility.

3. Key Contributions

• Quantification of Long-Term Risk: Unlike previous reports focusing on immediate impacts, this study provides a decade-long projection of how funding gaps translate into excess morbidity and mortality.
• Integration of TB-HIV Dynamics: The model explicitly demonstrates the feedback loop where reduced ART coverage drives higher HIV incidence, which in turn fuels TB transmission and mortality, highlighting the necessity of integrated care.
• Policy-Relevant Recovery Timelines: The study calculates the specific lag time required to return to baseline epidemiological trends even if funding is restored, emphasizing the "scarring" effect of temporary service disruptions.
• Contextualization of Domestic Response: The paper contextualizes modeling results against real-world mitigation efforts, such as the South African government's emergency funding and the "End TB Campaign," offering a nuanced view of potential outcomes.

4. Key Results

The modeling projects severe consequences under unmitigated scenarios, with significant variation based on the speed of recovery:

• HIV Impact:
  • Reduced ART coverage is projected to cause 235,000 to 1,000,000 additional HIV infections between 2025 and 2035.
  • The lower bound (235k) assumes recovery by 2029; the upper bound (1M) assumes no recovery.
• TB Incidence and Mortality:
  • Additional TB Episodes: Projected to range from 223,000 (7% increase) in a "minimal impact with recovery" scenario to 731,000 (24% increase) in a "maximal impact with no recovery" scenario.
  • Additional TB Deaths: Relative to a baseline of 481,000 deaths (2025–2035), the model predicts an additional 67,000 to 225,000 deaths.
• Impact on People Living with HIV (PLHIV):
  • TB episodes among PLHIV are projected to rise by 12–41%.
  • TB deaths among PLHIV are projected to rise by 21–72%.
• Recovery Lag: Even with a full restoration of services by 2029, the model indicates it would take an additional 8–12 years for TB incidence and mortality to return to the pre-crisis baseline trajectory.

5. Significance and Implications

• Reversal of Decades of Progress: The study warns that without rapid and sustained mitigation, South Africa risks erasing more than a decade of progress in TB and HIV control, potentially leading to a resurgence of the epidemic.
• The Cost of Delay: The findings underscore that temporary service disruptions have long-lasting "scarring" effects. Once transmission chains are re-established due to undetected cases, reversing the trend requires years of intensified investment.
• Domestic Resource Mobilization: While the South African government has allocated US$ 41.7 million in emergency funds (with US$ 32 million for HIV services), the study calls for greater transparency regarding TB-specific allocations and the exploration of alternative financing mechanisms (e.g., social impact bonds).
• Strategic Imperative: The results serve as a critical evidence base for policymakers to prioritize domestic funding, protect core services, and accelerate diagnostic innovations (e.g., point-of-care tests) and future vaccine integration to prevent avoidable illness and death.

In conclusion, the paper provides a stark mathematical demonstration that the withdrawal of US funding poses an existential threat to South Africa's TB and HIV control efforts, necessitating immediate, transparent, and sustained domestic intervention to avert a humanitarian crisis.