Research in the country suggests that even if some people were found to test negative in nasal swabs, anal swabs showed them as positive, indicating the presence of long term infection. Although the sample size is too small to determine anything, research is throwing up new avenues. While rapid antigen tests have been used in India to conduct quick tests in communities to determine infection, researchers found a new rapid testing technique. As per research in the ACS Sensors, Osaka University scientists discovered that they could detect virus particles by identifying changes in electric current as it passes through ultrasmall pores.
Last year, Chinese and American scientists started working on a DNA based test using Crispr Cas-12 and Cas-13 technique. India also moved to a similar test named Feluda, developed by CSIR-Institute of Genomics and Integrative Biology, which was the first in the world to use Crispr-Cas-9 technique. Used on 2,000 patients, the test had a 96% sensitivity and 98% specificity. The real benefit of the test is the turnaround time. While an RT-PCR test takes hours to determine results, Feluda can do so in 45 minutes. Two, it does not require advanced machines like the ones required for RT-PCR testing.
Not that RT-PCR testing itself has not gone through advanced iterations. Hologic Panther Systems was one of the first companies in the US to get an emergency use authorisation for its fully automated transcription-mediated application testing, which is somewhat similar to PCR. In October 2020, the FDA authorised Aptima SARS-CoV-2 assay to test individuals without symptoms given the sensitivity and accuracy.
MD & CEO, Hemogenomics Sumit Bagaria, company involved in getting diagnostic solutions to India explains how Hologic system machines are being used in India and their cost and safety aspect.
“When signals of Covid came in January or February, they were first to move into Covid test. The Panther system is a fully automated amplification system a bit different from PCR, but similar in the sense it amplifies the viral RNA or DNA. Hologic uses a technology called transcription-mediated application”, he says.
“The machine can do a 1,000 tests a day, and the company is doing 5 million tests a month, of which 4 million are in the US,” he adds.
The machine costs Rs 1.6 crore and Rs 2.5 crore with a five-year maintenance. The cost per test is `1,800-much higher than manual RT-PCR test-but Bagaria claims that the machine is more advanced and safer where swab goes directly in the tube and then directly in the machine, which is not the case with manual testing where tubes are changed often.
Another testing that has assumed importance is the antibody test, Roche recently got the FDA approval for its antibody test. Many countries are also using antibody tests to determine the relationship between vaccine protection and antibodies.