Not just RT-PCR, antibody tests could also help India win battle against Corona

New Delhi: As the number of COVID-19 cases in India rose above the 500-mark on Tuesday morning, Indian Council of Medical Research (ICMR) numbers showed that testing had been significantly increased in the last 24 hours. However, while the government has already approved a dozen private laboratories for testing, guidelines issued by the ICMR have recommended against the use of traditional PCR tests and antibody/antigen tests for detecting the virus, leading to a host of manufacturers in India trying to produce real-time RT-PCR test kits for supply in the private laboratories. So, how are the kits different from each other and what other testing methods could help India in its battle against the novel Coronavirus and can antibody tests help India?

It is crucial to understand that traditional PCR kits have been available and in use for decades now. An abbreviation for polymerase chain reaction, PCR tests are performed to identify the presence of a certain type of foreign molecule (DNA or RNA).

There have been concerns over why India is not using antibody tests - a relatively cheaper option - to test for COVID-19. But, these tests would not be conclusive enough to say whether the sample is positive for SARS-CoV-2 or not. In an antibody test, the kit will assess whether the sample is producing antibodies for the virus or not.

This means if the antibodies are detected, the sample could either still contain the virus or have had the virus at some point in the past. In essence, the test still will not be able to conclude whether the sample is positive for SARC-CoV-2 or not. But it may still be useful for Indian authorities to start conducting antibody tests.

These tests help to identify antibodies that are capable of fighting off SARS-CoV-2 which might go a long way in studying possible vaccinations for the COVID-19 and the nature of the virus in itself. Several experts across the world have said that antibody tests and the studies arising from it could go a long way in understanding how humans can develop an immunity to the novel Coronavirus.

After Chinese authorities published the genome sequence of the novel Coronavirus (SARS-CoV-2), tests were developed where certain enzymes are used to identify and amplify SARS-CoV-2 presence (now that the genome of the virus was sequenced) in a particular sample. An RT-PCR test is one where an enzyme known as reverse transcriptase is used to highlight the presence of the novel Coronavirus in a sample. However, real-time PCR kits were developed fairly recently, which allowed for more accurate and faster results.

The only difference between the two is that these test kits are able to identify the virus at an earlier stage of the reaction triggered by the enzyme. So, which is more definitive? The NIV in Pune has recently validated two RT-PCR test kit manufacturers citing a 100 per cent concordance with their true negative and true positive cases for both kits.

Experts in the field told Millennium Post that at this point in cases of a pandemic, it does not really matter which of these are used as long as they are validated by the required authorities. "Some of these are more accurate or more quantitative than the other but in such cases, all tests need to be able to do is identify the virus (irrespective of its quantity)," one of them said.