Thanks to the pandemic, scientific institutions in India have been able to demonstrate their ability to rise to the occasion and show why the country should increase funding for science research and development. The ICMR’s approval, recently, of two indigenously developed tests that are rapid, low-cost and have high sensitivity and specificity provides the much-needed boost to scale up daily testing without diluting accuracy. After carrying out about one million tests each day for the last few weeks, India, for the first time, tested nearly 1.5 million samples on October 21. While most tests done each day were the low sensitivity rapid antigen tests, the ones developed by the Delhi-based Institute of Genomics and Integrative Biology, a CSIR institute, and IIT Kharagpur will now enable the shift to more accurate tests. The low sensitivity of rapid antigen tests has meant that even people with symptoms were being handed out a negative result nearly half the time, leading to undetected cases. With unrestricted movement, businesses opening up, the festival season beginning and winter around the corner, the requirement for a rapid, low-cost test with high accuracy is crucial in checking the virus spread through early detection and repeated testing of even asymptomatic cases. Having locally developed tests with higher accuracy will now help States to offer tests on demand — as required in a September 4 ICMR advisory — while keeping costs low.
While the low sensitivity of rapid antigen tests arises from not isolating the viral RNA from the swab samples and amplification of the DNA before detection, the two indigenously developed tests follow these two vital steps, the reason why the sensitivity and specificity are far superior to that of the rapid antigen tests. But, at the same time, both the tests developed locally do require minimum laboratory infrastructure to isolate the viral RNA from the samples. For that reason, India has to still rely on rapid antigen tests in rural areas that have no laboratory infrastructure. But the tests developed by the Indian institutions, once commercially available, can readily replace the rapid antigen tests in places where such laboratory infrastructure is in place. Rapid antigen tests will become less important even in rural areas once research institutions succeed in developing protocols and tests for using saliva rather than swabs, and do not require isolation of viral RNA from patient samples before amplification and detection. Field testing and validation of such protocols is now pending. Relying on saliva samples would mean non-invasive sample collection, and probably even self-collection. Thus, the reliance on trained personnel would reduce and also minimise the risk of health workers getting infected.