The impact of USAID and CDC funding cuts on HIV incidence and mortality in KwaZulu Natal, South Africa

This study models the impact of abrupt USAID and CDC funding cuts in KwaZulu Natal, South Africa, revealing that such cessation would significantly increase HIV incidence and mortality by 2030, while restoring funds within 12 months and reallocating them to long-acting PrEP could substantially avert new infections and help realign the province with epidemic control goals.

The Gist

Imagine South Africa's KwaZulu-Natal (KZN) province as a massive, bustling city that has spent the last 20 years building a incredibly strong firewall against a dangerous virus (HIV). This firewall wasn't built with just local bricks; it was reinforced by a steady stream of supplies and engineers from two major international donors: USAID and the CDC.

Because of this support, the city has been winning the war. The virus is slowing down, and people are living longer, healthier lives.

The Sudden Power Outage

The paper describes a scary scenario that happened on January 25, 2025: The international donors suddenly flipped the switch and cut off their funding.

Think of it like a city that relies on a specific type of fuel to run its emergency generators. Suddenly, the fuel truck stops arriving. The generators don't stop instantly, but they start sputtering. Within a year, the city's defenses begin to crumble.

What the "Crystal Ball" Predicted

The researchers used a sophisticated digital simulation (a "crystal ball" made of math) to see what happens if this funding stays cut for 12 months, and what happens if it stays cut all the way to 2030.

Here is the bad news from the simulation:

• The Virus Spreads Faster: Without the funding, the number of new infections jumps. In just one year, it goes up by about 3%. By 2030, it could be nearly 23% higher than if the money had kept flowing.
• The Human Cost: This isn't just a number on a spreadsheet. The model predicts that over the next few years, this funding gap would cause 35,000 extra people to get infected in just one year, and eventually 116,000 extra infections by 2030.
• Tragic Loss of Life: Consequently, 12,800 extra people would die in the first year alone, rising to 42,300 extra deaths by 2030.

It's as if the city's fire department had to stop patrolling certain neighborhoods. The fires (infections) start spreading, and more houses (lives) are lost.

Why Did This Happen?

The study found that the money cuts hit two main areas:

1. Running Out of Medicine: About 31% of the new infections happened because people couldn't get their life-saving HIV medication (ART).
2. The USAID Factor: About 43% of the new infections were directly linked to the specific programs USAID was funding.

The total cost of this "power outage" is about $59.3 million per year. That's the price of the supplies and engineers that suddenly vanished.

The Lifeline: A Smart Pivot

Is there hope? Yes, but it requires a clever strategy.

The researchers found that if the funding comes back within 12 months, the city can recover. But there's a catch: How the money is spent matters.

Imagine you have a limited budget for fire extinguishers. You've been buying small, handheld ones (Oral PrEP) that people often forget to use every day. The study suggests that if you take that same budget and buy high-tech, long-lasting fire extinguishers (Long-Acting PrEP) that last for months and don't require daily effort, you get much better protection.

• The Magic Trick: If the funding is restored and switched to these "long-acting" tools, the model predicts they could prevent 12,600 of those extra infections that would have happened during the 12-month gap. It's like upgrading from a leaky bucket to a high-pressure hose; you get more protection for the same amount of money.

The Bottom Line

This paper is a wake-up call. It tells us that the progress made over two decades in fighting HIV in KZN is fragile. If the international community stops paying the bills, the virus will roar back, undoing years of hard work and costing thousands of lives.

However, if the funding is restored quickly and used smarter (by switching to longer-lasting prevention tools), the city can rebuild its firewall and get back on track to completely ending the epidemic. The choice is between a slow, tragic decline or a smart, efficient recovery.

Technical Summary

1. Problem Statement

The study addresses the critical threat posed by the abrupt cessation of United States Agency for International Development (USAID) and U.S. Centers for Disease Control and Prevention (CDC) funding to KwaZulu-Natal (KZN), South Africa, effective January 25, 2025. KZN hosts the largest HIV epidemic globally and relies heavily on these external resources to sustain its antiretroviral therapy (ART) and prevention programs. The authors sought to quantify the projected impact of a 12-month funding pause (and potential permanent cuts) on HIV incidence and mortality through 2030, and to evaluate whether reallocating remaining resources toward more efficient interventions (specifically Long-Acting PrEP) could mitigate these negative outcomes.

2. Methodology

The researchers employed a Participatory Policy-guided Modeling (PPM) approach using a validated, compartmental HIV transmission model previously adapted for the KZN context.

• Model Structure:

  • Compartments: The model stratified the population by sex, age groups (<15, 15–24, 25–34, 35–64, ≥65), HIV risk levels (low, medium, high), risk types for men (MSM vs. non-MSM), genotypic resistance (wildtype vs. resistant), and the presence of Conditions of Alcohol, Substance, and Mood (CASM) disorders.
  • Disease Progression: The model simulated five sequential stages of HIV infection: Susceptible, Acute, Chronic, Advanced, and HIV-related Death. Each stage was further subdivided by diagnosis status, ART treatment status (adherence/retention), and viral load suppression.
  • Transmission Dynamics: Transmission was modeled via vertical and horizontal sexual routes (injection drug use was excluded as uncommon in KZN). Risk levels were defined by the number of concurrent sexual partners.

• Data Inputs & Calibration:

  • Inputs were derived from annual workshops with the KZN Department of Health, local clinicians, academics, and civil society.
  • Key parameters included HIV prevalence, incidence, viral load suppression rates, ART adherence (63%), and linkage to care probabilities.
  • Costing: An ingredients-based micro-costing approach was used to determine intervention costs (e.g., Long-Acting PrEP at $144/patient/year vs. Oral PrEP at $87.52/patient/year).

• Scenarios Simulated:

  1. Funding Cuts: Simulated an instantaneous cessation of USAID and CDC funding for 12 months, with effects projected through 2030.
  2. Restoration: Modeled the impact of restoring funds after a 12-month pause.
  3. Reallocation: Evaluated a scenario where funds saved from oral PrEP were reallocated to Long-Acting PrEP (LA PrEP), assuming LA PrEP costs no more than 1.5 times that of oral PrEP but offers higher retention (60–90% vs. 10–30%).

3. Key Contributions

• Real-Time Policy Modeling: Unlike previous studies that assumed hypothetical cuts, this study utilized specific programmatic data and expert opinion gathered in March 2025 to model the actual funding cuts affecting specific interventions (USAID vs. CDC).
• Granular Stratification: The study distinguished between the impacts of USAID cuts alone, CDC cuts alone, and combined cuts, providing a nuanced view of which programs are most vulnerable.
• Efficiency Optimization: The paper introduces a mitigation strategy involving the reallocation of resources from lower-efficacy oral PrEP to higher-efficacy Long-Acting PrEP, demonstrating how operational efficiency can offset funding losses.
• Participatory Approach: The use of PPM ensures that model inputs reflect the priorities and realities of local stakeholders, increasing the validity of the projections for policy implementation.

4. Key Results

• Projected Increases in Incidence and Mortality:
  • 12-Month Impact: HIV incidence is projected to increase by 3.4% within one year.
  • Long-term Impact (through 2030): Incidence is projected to rise by 22.8%.
  • Absolute Numbers: These increases translate to approximately 35,300 additional infections at 12 months and 116,100 additional infections by 2030.
  • Mortality: The cuts are projected to cause 12,800 additional deaths at 12 months and 42,300 additional deaths by 2030.
• Attribution of Risk:
  • Approximately 43% of the added infections are attributable to USAID cuts alone.
  • Approximately 31% of added infections are due to decreases in ART supply.
  • The total annual funding loss is estimated at $59.3 million (USAID: ~$22.8M; CDC: ~$36.5M).
• Mitigation via Reallocation:
  • If funds are restored after a 12-month pause and reallocated from oral PrEP to Long-Acting PrEP, the model predicts the avertance of 12,600 additional infections by 2030.
  • This reallocation strategy could effectively offset the incidence increase caused by a funding pause of 12 months or less, provided the cost multiplier for LA PrEP remains below 1.5x oral PrEP.

5. Significance and Conclusion

• Threat to Global Goals: The study concludes that the sudden withdrawal of US funding threatens decades of progress in KZN and undermines global efforts to "End the HIV Epidemic" (EHE).
• Reversibility: The findings suggest that the damage is not irreversible if funding is restored within 12 months. However, restoration alone is insufficient; it must be paired with increased efficiency (e.g., shifting to Long-Acting PrEP) to fully reestablish the province's trajectory toward EHE goals.
• Policy Implications: The authors emphasize that while the study has limitations (e.g., assuming instantaneous scale-up/down and ignoring supply chain friction), the results provide a stark warning. They call for immediate action to restore funding and optimize resource allocation to prevent a catastrophic resurgence of HIV in one of the world's most affected regions.

Note: As this is a preprint posted on medRxiv, the authors explicitly state that the research has not yet undergone peer review and should not be used to guide clinical practice without further validation.