A new paper-based test from India may be a gamechanger for coronavirus testing. The new kit, named after the fictitious Bengali detective Feluda, is accurate, can return results within an hour, and only costs less than seven dollars.
The test strip, similar to a pH level paper strip or a pregnancy test, was created using CRISPR (Clustered Regularly Interspaced Short Palindromic Repeat), a genetic engineering technique. Feluda is developed by India's TATA Medical and Diagnostics Ltd.
Working alongside the Institute of Genomics and Integrative Biology (IGIB), where the paper-based test was developed, its test is "simple, precise, reliable, scalable, and frugal," shared Professor K Vijay Raghavan. Around 2,000 patients had been tested with Feluda, including those who had previously tested positive for the virus.
Accuracy & Sensitivity of Feluda
Test accuracy was 96 percent sensitive and 98 percent specific. The test's sensitivity is to detect who is positive, while specificity indicates negative results.
The two proportions also decrease false negative and false positive results compared to other types of tests. Fulda has also been cleared for commercial production and use.
India ranks second in the highest number of confirmed infections after the United States at more than six million positive cases. They've surpassed Brazil, who ranked second for months, who has almost five million positive cases.
Feluda has proven to be more precise than the polymerase chain reaction (PCR) test and is nearly five times cheaper. Before Feluda, India has been conducting PCR swab tests and the antigen test, a finger-pricking method similar to a blood sugar device for diabetes. However, the antigen test has proven to generate several false negatives.
Dr. Anant Bhan shared that many Indians have to wait long for test results and also deal with the unavailability of kits. Conducting mass rapid antigen testing also means dealing with a lot of false negatives, he shared. Feluda may soon replace the antigen tests since it is cheaper and more accurate, Dr. Bhan believes.
Feluda has the same reliability of the PCR test, but with faster results and does not need sophisticated equipment, shared Dr. Anurag Agarwal from IGIB. Feluda is composed of a nasal swab test that is sent to a lab where CRISPR technology analyzes the sample and gives the results on a piece of paper. Two blue lines indicate positive, while a single line indicates negative for coronavirus.
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Developing Paper-Based Tests
Dr. Stephen Kissler from Harvard Medical School said that Feluda would help India make testing more widely available. Researchers from the United States and the United Kingdom are also working on similar CRISPR and paper-based tests.
Dr. Thomas Tsai from Harvard Global Health shared that ideally, the ultimate test would be a paper-based test that people can take at home. However, extracting and amplifying RNA requires specific technology not available for home kits.
Feluda's developers are working on precisely that, a prototype test where people can extract and amplify RNA from swab tests at home. They are trying to create a prototype that is "machines and manpower do not limit a simple, affordable, and truly point-of-care test so widespread testing," shared Feluda developer, Dr. Debojyoti Chakraborty.
Read Also: Researchers Demonstrate New Portable and Point-of-Care COVID-19 Test Kit
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