As diagnostic technologies evolve, they often become more sophisticated, requiring advanced infrastructure, greater energy used, and specially trained personnel. While these advancements can enhance diagnostic accuracy and speed in well-resourced settings, they also make these tools increasingly out of reach for low- and middle-income countries (LMICs). In many regions, the cost of equipment, the need for cold chain storage, or the requirement for specialized training create significant barriers to implementation. This can lead to diagnostic gaps, particularly in areas where timely diagnosis could prevent the spread of infectious diseases or improve patient outcomes.
Lateral flow assays (LFAs) or Rapid Diagnostic Tests (RDTs) and other point-of-care tests (POCTs) continue to offer compelling solutions to these challenges. Designed for use in decentralized and/or resource-limited environments, LFAs are simple to use, affordable, and are often designed so as not to rely on energy-hungry equipment or highly trained personnel. These attributes make them ideal for improving access to healthcare in LMICs, where more complex diagnostic systems often fail to reach the population in need.
In this article, we present 7 practical strategies for developers working to design lateral flow assays for LMICs, drawing on DCN Dx’s expertise in developing IVDs for these unique environments. From designing robust, affordable tests to ensuring successful manufacture, field deployment and integration with local healthcare practices, these strategies are designed to help developers create impactful, sustainable diagnostics that help meet the real-world needs of LMICs.
That said, the strategies outlined here are generalized. For tailored guidance or questions about a specific project, please feel free to contact us for expert advice on your assay development needs.
1. Understanding the Needs of Low-Resource Settings
When developing lateral flow assays for low-resource settings like LMICs, the first step is a thorough understanding of the environment where the test will be deployed and who will be using the test. In these regions, infrastructure is often limited. Hospitals or clinics may lack consistent electricity, laboratory space, or trained personnel, making traditional diagnostic technologies commonly used elsewhere, such as PCR or blood culture systems, unfeasible.
Environmental factors—such as extreme temperature and humidity—can also significantly impact the performance of an LFA. These conditions can degrade sensitive reagents and materials, leading to inaccurate results. Developers must prioritize the creation of assays that maintain stability across a broad range of temperature and humidity conditions while also often ensuring that the test is simple to use for public health workers or the public with minimal diagnostic training.
2. Reagent and Material Selection: Stability is Key
One of the most critical factors in designing LFAs for LMICs is ensuring that reagents remain stable over time and across a wide range of environmental conditions. This typically involves selecting materials and components that can withstand temperature fluctuations and humidity, both during use and throughout storage and transport in low-resource settings.
Key Considerations:
- Humidity Resistance: Humidity can degrade many test components, particularly paper-based materials. Careful formulations and packaging material selection can mitigate this. Incorporating desiccants or multi-layered packaging with moisture-barrier films into the design helps protect the test from environmental moisture, ensuring long-term viability, especially in high-humidity environments.
- Heat Sensitivity: While most LFAs are designed to avoid cold chain storage, certain reagents, such as antibodies or enzymes, may still be sensitive to heat. Using heat-stable reagent formulations can mitigate this risk, ensuring test stability even when exposed to high ambient temperatures, which can regularly exceed 30°C (86°F) in LMICs.
- Shelf Life: In remote regions, tests must usually have a long shelf life to reduce the logistical burden of frequent resupply. Ensuring that the assay has a shelf life of 12-24 months or longer is often ideal, especially for diagnostics intended for stockpiling or gradual deployment over time.
3. Sensitivity and Specificity: Striking the Right Balance
For developers, balancing sensitivity and specificity is a critical challenge, especially in LMICs where false positives or false negatives can have significant public health implications. For example, during the 2014-2016 Ebola outbreak in West Africa, LFAs were rapidly deployed to provide quick and accurate diagnoses in the field, and were especially useful for “‘rule in’ tests to expedite treatment and vaccination.” In such high-stakes scenarios, misdiagnoses could lead to missed cases, causing further spread, or to unnecessary treatments, quarantines or concerns within communities. LFAs need to perform reliably in environments with high disease prevalence but limited diagnostic resources, where a misdiagnosis can have serious consequences.
Key Challenges:
- Maintaining High Sensitivity: Sensitivity measures how well the test identifies true positives. In resource-limited settings, LFAs often target diseases with high prevalence, such as malaria, HIV, or tuberculosis. Ensuring that these tests can reliably detect low pathogen loads or early-stage infections is crucial. Developers need to choose highly sensitive antibodies or binders and optimize the assay’s detection limit to capture these cases without requiring complex instrumentation. However:
- Tradeoffs: Developers must also consider trade-offs between sensitivity and specificity. Improving sensitivity might reduce specificity, leading to more false positives, which can strain resources by requiring unnecessary treatments.
- Ensuring Specificity: Specificity measures how well the test identifies true negatives, avoiding false positives that could lead to inappropriate treatments. In LMICs, where access to confirmatory tests is limited, LFA developers must focus on designing assays that minimize cross-reactivity with similar pathogens while ensuring accuracy in the intended disease. Field conditions, sample quality, and handling variability in LMICs can impact test performance, making it critical for developers to design POCTs that remain robust despite these challenges.
Strategies for Developers:
- Improved Antibody Selection: Developers should prioritize high-affinity antibodies or alternative binding molecules that demonstrate minimal cross-reactivity, ensuring that the assay can distinguish between similar pathogens.
- Optimization of the Detection System: Signal optimization techniques or multi-analyte testing can be employed to ensure that the assay performs well even at low analyte concentrations, while minimizing the risk of false positives.
4. Simplifying the User Experience: Designing for Non-Expert Users
In LMICs, often the individuals administering lateral flow tests may not have a formal medical training, and they might be triaging large numbers of patients at a time. As such, lateral flow assays for low-resource settings must usually be designed with simplicity and usability in mind. The goal is to minimize the risk of user error while still delivering accurate results.
Best Practices for Usability:
- Clear, Intuitive Interfaces: Tests should be easy to interpret, ideally with a simple positive/negative readout. Visual clarity is essential, particularly in settings where access to training or guidance materials may be limited. Developers should also consider the diversity in literacy levels and languages across LMICs, making it important to test user interfaces in local contexts to ensure they are universally understood.
- Minimal Handling Steps: Reducing the number of steps in the assay procedure helps decrease the likelihood of user error. In our experience, designing a test that can be administered in as few as 2-3 steps, with clear instructions, dramatically improves accuracy in the field. Incorporating error-proofing mechanisms, such as visual or audible feedback for improper sample loading, can also further reduce mistakes.
- Robust Packaging: Assays should be robustly packaged to protect against environmental conditions, such as moisture or dust, without compromising ease of use. Packaging design should also factor in ease of opening and handling for non-expert users, who may be working in stressful, high-volume settings.
- Training and Education Materials: While LFAs are most often designed for simplicity, providing easy-to-understand educational materials can further minimize user errors. Pictorial instructions, videos, or even smartphone-based tutorials can supplement the use of the test, particularly in regions with low literacy. These materials should be culturally adapted and localized to meet the specific needs of the target population.
5. Regulatory and Field-Use Validation: Ensuring Global Compliance
One of the most significant hurdles in bringing a diagnostic test to market in LMICs is ensuring that the assay meets both local and international regulatory standards. Organizations like FIND Dx often work closely with developers to guide products through these regulatory processes, with the WHO prequalification system being a critical benchmark for many LMICs.
Key Considerations:
- WHO Prequalification: Many LMICs look to WHO prequalification as a benchmark for quality, safety, and performance. WHO prequalification allows tests to be procured by international health organizations and governments. Developers must align their design, validation, and production processes with WHO’s stringent criteria to ensure that the LFA can be distributed and used in these regions. WHO prequalification is often a key requirement for tests to be funded or purchased by organizations such as the Global Fund, UNICEF, or Gavi.
- Local Regulatory Approvals: While WHO prequalification is often essential for international distribution for some specified RDT’s, developers must also navigate the regulatory requirements of individual countries. This often involves adapting test documentation and processes to meet specific national standards, which can vary widely across LMICs.
- Field Validation: Validating LFAs in the environments where they will be used is critical. Field trials in real-world settings help ensure that the test performs as expected under the varied conditions encountered in LMICs, such as extreme temperatures, humidity, and differing levels of healthcare infrastructure. These trials provide valuable feedback from healthcare workers and local regulators, which can help refine the test and address usability or performance challenges before widespread rollout.
By engaging in early field validation and adhering to both international and local regulatory guidelines, developers can streamline the path to market, ensuring that their diagnostics meet the needs of LMIC populations and can be procured and distributed effectively.
6. Balancing Affordability and Performance
Cost constraints are a critical concern for diagnostic tests in LMICs, but cutting costs cannot come at the expense of accuracy or reliability. Developers must strike a balance between designing an affordable test and ensuring that it still meets high-performance standards, particularly in terms of sensitivity and specificity.
One of the most significant challenges developers face is navigating the trade-offs between cost and expensive reagents like antibodies or antigens to ensure optimum test performance meeting target specifications. Reducing production costs may impact factors such as robustness, durability, or shelf life, all of which are essential for tests used in resource-limited settings. The goal is to find cost-effective reagents without compromising the performance or consistency of the test.
While I have caveated this entire article that this is generalized advice, this tradeoff between cost and performance is an especially difficult one because cost issues must be addressed early in the development process. I cannot stress enough the importance of keeping this tradeoff between cost and performance constantly in mind. If you are struggling with this, ask how we can help.
Strategies for Cost Optimization:
- Material and reagent costs: Minimizing materials (size) and reagents (amounts used) without compromising sensitivity can lower the overall cost per test. Careful material selection also allows for cost reductions while maintaining the necessary quality for high performance.
- Manufacturing Scalability: From the outset, developers should design their LFAs with scalable manufacturing in mind. Automated manufacturing processes can drive down costs significantly, but the test design itself must lend itself to high-throughput production while maintaining consistency in performance across batches. Quality control processes must be integrated to ensure the reliability of the tests, even as production scales up.
- Sustainability Considerations: In the pursuit of cost savings, sustainability is an increasingly important factor. Using recyclable or biodegradable materials, or designing assays that minimize plastic waste, can contribute to long-term affordability by reducing environmental impact. However, these sustainable materials can be expensive and these initiatives must be balanced with ensuring that the test remains affordable for LMICs. Our Principal Engineer recently released a great video on this topic.
7. Supply Chain and Scalability: Overcoming Logistical Challenges
A significant challenge when developing LFAs for LMICs is ensuring that the test can be produced at an appropriate cost effective scale and distributed reliably. These countries often lack the robust supply chain infrastructure found in high-income countries, and delays or shortages can critically impact access to diagnostic tests. Ensuring supply chain flexibility, quality control during scale-up, and efficient distribution are critical to overcoming these barriers.
Strategies for Supply Chain Resilience:
- Local Manufacturing Partnerships: Establishing local production partnerships can help reduce dependency on international supply chains, and potentially lower production costs for some kit components, and shorten delivery times. Local partnerships can also facilitate quicker adaptation to region-specific needs or regulatory changes, making the supply chain more resilient to disruptions. However, key reagents like antibodies and antigens or key materials like nitrocellulose membrane and conjugate pads may only be available via international supply, therefore import and transport costs must be considered as part of any bill of material cost analysis
- Scalable Manufacturing Processes: Developing manufacturing processes that are easily scalable ensures that once demand for the LFA grows, it can be produced and delivered in large quantities without compromising quality or significantly increasing costs. However, it is crucial to maintain strict quality assurance protocols during scale-up to prevent issues that could arise from changes in production volumes or facilities. Conversely, many RDTs required in LMICs are focused on niche diagnostic needs that are geographically specific and have limited volume requirements. Therefore material and labor cost analysis needs to address low volume low batch size productions runs in addition to scenarios where demand can grow significantly.
- Supply Chain Flexibility: Developers must design flexible supply chains that can withstand potential disruptions, such as geopolitical tensions, raw material shortages, or transportation delays. Building in multiple logistics options for procurement of the validated raw materials and diversifying manufacturing sites can potentially help safeguard against these risks.
- Logistics for Hard-to-Reach Areas: If they aren’t already, developers should consider partnering with NGOs, local health ministries, or local distributors that already have distribution networks in place, especially for rural or remote areas where health infrastructure is limited. Leveraging existing logistical frameworks can help ensure that tests reach under-served populations quickly and efficiently.
- Packaging Solutions: Ensuring that your tests are packaged robustly to handle harsh environmental and transport conditions is critical for successful distribution.
- Inventory Management and Distribution Strategy: Where reliable infrastructure exists, establishing regional warehouses or inventory management systems can help optimize distribution, reducing the time it takes for tests to reach healthcare providers in these regions.
Conclusion: Designing for Impact
Developing lateral flow assays for low- and middle-income countries requires a practical, thoughtful approach that balances performance, cost, and usability. By focusing on environmental stability, simplifying the user experience, optimizing for affordability, and ensuring a robust supply chain, developers can create diagnostics that are not only effective but also accessible in resource-limited settings.
At DCN Dx, we are committed to advancing global health through the development of high-quality IVDs that meet the unique needs of low-resource environments. By following these practical design strategies—prioritizing bill of material costs, scalability, and usability—developers can make a significant impact in bridging the diagnostic gap in under-served regions, improving healthcare outcomes in LMICs.
If you have questions about how to develop lateral flow assays for low-resource settings or need expert guidance on your other IVD CDMO or CRO projects, contact us to learn how we can support you in bringing impactful solutions to these under-served markets.
