New Analysis in The Lancet HIV Warns That WHO’s Three-Test Diagnostic Algorithm May Be Slowing Access to Lifesaving HIV Treatment
A new Correspondence Letter published in The Lancet HIV by the AIDS Healthcare Foundation (AHF) is drawing global attention to a growing concern in HIV diagnosis: whether the World Health Organization’s (WHO) recommended three-test algorithm, introduced to minimize already rare false-positive results, may be unintentionally delaying when individuals begin antiretroviral therapy (ART). While the guideline was designed with the important goal of ensuring maximum diagnostic accuracy, evidence from frontline HIV programs suggests that the additional steps required for a third rapid test could be slowing treatment initiation—particularly in clinics already strained by staff shortages, supply constraints, and increasing patient volumes.
According to the AHF authors, the challenge is not with the intent behind WHO’s guidance but with its practical impact in real-world health-care environments. Many health facilities, especially those in low- and middle-income countries (LMICs), are operating with limited personnel, inadequate budgets, and inconsistent access to diagnostic supplies. Requiring three separate rapid tests—performed sequentially in a strict algorithm—adds operational complexity to an already demanding workflow. As the Letter argues, the consequences of this complexity can be significant, ultimately affecting how quickly newly diagnosed individuals are linked to treatment.
Operational Challenges on the Ground
AHF teams working in several countries, including Kenya, Uganda, Nigeria, and parts of Latin America, have reported that the three-test policy has created unintended logistical bottlenecks. In many busy clinics, patient flow relies on efficient coordination among various health workers—triage staff, counselors, laboratory technicians, and ART clinicians. A testing algorithm that requires three distinct rapid tests, each administered and documented correctly, often means that individuals must move between multiple service points or wait for different staff members to become available.
In Kenya, for example, AHF-supported facilities have noted that conducting three rapid tests during a single visit often stretches the testing process well beyond what most clinics can accommodate in a typical day. In settings where HIV testing is integrated into broader primary care, maternity services, or community outreach programs, the additional steps can lead to backlog, longer queues, and greater risk that people leave before completing the full diagnostic process. When clients must return on another day to complete testing or begin treatment, attrition becomes more likely. As a result, individuals may not start ART promptly despite having two clear positive rapid test results, a delay that contradicts the global “test-and-treat” approach endorsed by WHO itself.
False Positives Are Already Extremely Rare
A central argument presented in the Letter concerns the rarity of false-positive HIV results when high-quality rapid tests are used correctly. WHO’s three-test recommendation was introduced with the caution that in populations with decreasing HIV prevalence, even highly specific tests can produce occasional false positives. However, AHF points out that with proper training, consistent quality assurance systems, and the use of two different rapid tests with strong specificity, the probability of a false-positive diagnosis remains extremely low.
Numerous HIV programs worldwide have long relied on two-test algorithms without encountering significant issues related to misdiagnosis. Furthermore, the Letter notes that today’s rapid tests are more accurate than those used a decade ago, reducing the additional value that a third test may provide. In well-run clinics where standard quality control procedures are in place, the incremental benefit of a third rapid test may be outweighed by its downsides—chiefly, operational inefficiency and delayed treatment.
An Alternative Path: Treat After Two Positive Rapid Tests
To address these challenges, the authors highlight a practical alternative strategy already adopted in several countries, including Brazil: initiating treatment after two positive rapid tests while simultaneously sending a blood sample for a confirmatory viral load (VL) test. The rationale is simple—if the VL test later shows that the patient does not have HIV, treatment can be safely discontinued early without long-term harm. This model leverages modern verification tools that were not as widely accessible when older diagnostic protocols were first designed.
Brazil’s approach, among others, demonstrates how countries can protect diagnostic accuracy without requiring patients to navigate lengthy testing procedures before accessing treatment. The model also aligns with the growing global emphasis on same-day ART initiation, which has been shown to improve long-term retention in care and viral suppression rates. By reducing delays between diagnosis and treatment, the two-test-plus-viral-load model supports better individual and public health outcomes, including reduced risk of onward transmission.
Balancing Accuracy and Accessibility
The Letter emphasizes that diagnostic accuracy remains essential—and the goal is not to weaken safeguards but to balance them with the urgent need for timely treatment. Delays in ART initiation can have serious implications. For individuals newly diagnosed with HIV, beginning treatment promptly helps reduce viral load, preserve immune function, and prevent progression to AIDS-related illness. From a public health perspective, earlier treatment reduces community transmission, supports “treatment as prevention,” and strengthens progress toward ending the HIV epidemic.
The authors argue that the global HIV response cannot afford operational models that unintentionally create barriers to care, especially given the increasing complexity of health systems and the persistent inequalities affecting marginalized populations. Clinics with limited staff and heavy patient loads often struggle the most with multi-step diagnostic protocols, making it essential for guidelines to reflect ground realities.
Modern Verification Tools Offer New Flexibility
Another key point in the Letter is the growing availability of accurate and fast verification technologies. Besides traditional viral load tests, many countries now have access to rapid molecular platforms, fourth-generation antigen/antibody assays, or automated laboratory systems with high throughput and short turnaround times. These tools can confirm diagnoses with high accuracy without placing additional burdens on point-of-care staff.
Rapid molecular tests, such as cartridge-based nucleic acid assays, are becoming especially valuable in remote or resource-limited settings because they can be performed close to the point of care and produce results within hours. Similarly, fourth-generation assays—which detect both antibodies and viral antigen—provide another reliable method for confirmation when needed. As the authors note, these technologies offer viable alternatives to the traditional third rapid test, creating opportunities for more efficient testing workflows.
Tailoring Policies to Local Realities
The Correspondence Letter ultimately encourages national health authorities to adapt HIV testing algorithms to suit local circumstances. Countries with strong supply chains, well-staffed clinics, and consistent access to rapid tests may find that a three-test algorithm works without significant burden. However, in settings where the additional test creates bottlenecks or slows treatment initiation, adopting a more flexible approach—such as the two-test-plus-viral-load strategy—may be more beneficial.
AHF concludes that modernizing HIV testing policies in this way can help ensure both accurate diagnosis and rapid treatment, two goals that are central to achieving global targets, including the UNAIDS 95-95-95 goals for 2030. By reducing delays and simplifying the testing-treating continuum, health systems can support better outcomes for patients while maintaining the accuracy needed for responsible clinical practice.
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