TB diagnostic classes and products

The product list presented here is no longer included in the latest version of the WHO Consolidated guidelines on TB – Module 3: Diagnosis. This change reflects the growing role of WHO in vitro diagnostic PQ in TB diagnostic eligibility for WHO endorsement and UN organization procurement.

WHO announced the introduction PQ for TB diagnostics in 2021. PQ assesses the performance, quality, and safety of individual testing products within each diagnostic class. PQ procedures for all classes of TB nucleic acid tests became available in 2022, followed by procedures for point-of-care antigen-based lateral flow tests (such as LF-LAM) and Mycobacterium tuberculosis-specific antigen-based skin tests (TBSTs) in 2024. Most recently, in 2026, PQ was established for targeted next-generation sequencing solutions and interferon gamma release assays (IGRAs). TB culture and culture-based drug susceptibility testing, sputum smear microscopy, and tuberculin skin tests remain recommended for TB, DR-TB and TB infection diagnosis but are not currently planned for PQ assessment.

As recommendation-endorsed products undergo PQ assessment before established deadlines, and new within-class products are submitted for PQ assessment, it is expected that the specific products endorsed by WHO will change and the list will be updated.

Changes to the list of TB diagnostic products recommended by WHO are documented in Table 2. Products that were previously, but are no longer, recommended by WHO may be re-evaluated for future recommendation if they successfully achieve WHO prequalification listing in the future. This applies to products that miss established PQ assessment deadlines, are withdrawn by manufacturers, do not achieve prequalification, or are suspended or delisted by WHO PQ (more information: Overview of WHO’s prequalification procedure for in vitro diagnostics (2025)).

UN agencies, international and intergovernmental procurement organizations, or WHO Member States may use WHO policy recommendation and WHO prequalification listing, among other eligibility criteria, to inform procurement decisions according to their procurement and quality assurance policies.

Overview of WHO TB diagnostic class determination and new product assessment

WHO organizes TB diagnostics into classes of products rather than assessing individual products alone. New diagnostic products are assessed through a stepwise process that starts with class determination by the WHO Department for HIV, TB, hepatitis and sexually transmitted infections (WHO/HTH) and then, based on the outcome, proceeds through either WHO/HTH, WHO Prequalification Unit, or combined assessment pathways.

WHO/HTH assessments evaluate the accuracy, clinical impact, resource requirements, cost-effectiveness, equity, and feasibility and acceptability of new classes of diagnostics, while WHO PQ assessments evaluate the safety, performance and quality (including labelling, quality management and manufacturing) of individual tests. The processes for new product assessment are summarized below and further detailed in the latest edition of the WHO Consolidated guidelines on TB – Module 3: Diagnosis, second edition.  

Class determination by WHO/HTH is done to compare the characteristics of each new TB testing product against the characteristics that define each existing class of diagnostics (1). If a product’s characteristics differ from existing classes, it is assessed through Pathway A; if they are shared with an existing class, it is assessed through Pathway B.

Pathway A applies to "first-in-class" technologies whose characteristics differ from existing classes. These undergo evidence synthesis and recommendation development through the WHO guideline process using GRADE methodology, supported by a guideline development group (GDG). GDG-recommended technologies are referred for WHO Prequalification (PQ) assessment where a procedure exists or remain recommended by WHO/HTH until a procedure is established.

Pathway B applies to "within-class" technologies that share characteristics with an existing class. Where a PQ procedure is available, manufacturers proceed directly to PQ submission and successful listing constitutes WHO endorsement; where none yet exists, the technology undergoes WHO/HTH assessment facilitated by the WHO Technical Advisory Group on TB Diagnostics and Laboratory Strengthening. Resulting policy guidance on the new product stands until a PQ procedure for the class becomes available.

Irrespective of assessment pathways, once a prequalification procedure for WHO/HTH-recommended products becomes available, it should be successfully completed within two years of the publication date to maintain WHO endorsement and eligibility for global procurement by organizations whose quality assurance purchasing policies rely on WHO recommendations. Table 1 presents the current list of TB diagnostic classes and included products recommended and/or prequalified by WHO for diagnosis of TB, drug-resistant TB, and TB infection. Table 2 summarizes changes to the product list since the first 2025 edition of the WHO Consolidated guidelines on tuberculosis – Module 3: Diagnosis.