The Piano Lab

TLDR; 70% of TB testing in India is done using a test as good as a coin-toss. If we’re really serious about helping the millions of people that get TB, and will get TB in India every year, we need to accept our hubris, and use the advantage India already has. Not just the promise of technology.

We need to target Community Transmission, not just diagnosis

There were 2.5 million new TB cases in India in 2023, up from 2.4 million in 2022. India’s TB diagnostic infrastructure is sufficiently scaled but presents an opportunity for even more efficient screening and surveillance owing to patient behavior. There are ~30,000 District Microscopy Centers; microscopy remains the most common diagnostic modality despite limited sensitivity (50%) due to low cost and availability. There are about ~6,000 nucleic acid amplification test (NAAT) centers; molecular testing is highly sensitive but expensive and suffers from high volumes, slow turnaround times. Supply chain issues abound with poor state to state purchase and demand process visibility. This is compounded by the extreme stigma that still persists in India and causes use of diagnostic infrastructure in unique ways – Community Health Workers (CHW) interviews in Pune revealed that patients don’t even go to their nearest TB center but attend centers that are further away due to fears of being found out. This creates unique challenges for NAAT centric models. South Africa, for example, in the last decade has seen improved treatment outcomes, but a stable number of new TB cases, despite almost singular exclusive use of NAAT. This again hints at the main problem we need to target. Diagnostic access is an important, but ultimately, downstream effect of the larger TB problem: Community Transmission. Without finding patients actively, and in huge numbers, before they transmit, tuberculosis control will remain an uphill battle. This is especially important considering over 40% of cases in India are subclinical and will likely miss current symptom-based Active Case Finding (ACF) approaches. India, therefore, needs a unique strategy that can leverage both new and old infrastructure in reaching patients in a timely and active manner.

In any LMIC setting, scale, distribution and commercial viability are as important as the novelty of the product. There is a need for a 10x performance improvement in diagnostics that fits into the existing healthcare workflow for diagnosis of TB in India. Despite government mandate and rollout, over 75% of TB testing in India was done using microscopy, i.e., ~19 million tests in 2024, up from 14 million the year before. Even if India completely replaces NAAT over the next 7 years, it is likely that over 100 million patients will have used microscopy. Use of existing District Microscopy Centers can really increase the number of cases found and treated as the country transitions to molecular diagnostics.