The need of the hour
- For reliable antibody testing kits, India will have to make its own, according to independent epidemiologists and biotechnologists.
- Much like home-based pregnancy tests, antibody tests are valuable because they give results quickly and only needs a pinprick’s worth of blood.
- However, they can only detect antibodies produced by the immune system in response to the virus and this can take as many as 7-14 days to manifest.
- The initial expectation was that an antibody test would soon be available. But it was the PCR technology that came first. That’s also due to the fast-moving nature of the virus.
Difference between PCR and Antibody test
- The PCR technology is confirmatory because it identifies the SARS COV-2 based on genes, whereas the presence of viruses has usually been detected via antibody kits by the proteins produced by the virus’s genes.
- An antibody test only tells you whether a person has ever been infected by the virus.
- These antibodies that are produced are not necessarily specific to SARS COV-2 and could even be generated by a variety of other pathogens.
- There are other 4 other common coronaviruses and antibodies could be generated to that too.
- So far, nobody has found a protein that’s specific to SARS COV-2.
How are we conducting the tests?
- The ICMR’s current recommendation is to test those who show symptoms such cough, fever and breathlessness and even a sore throat. After quarantining for 14 days, an antibody test is to be done and if positive, the person ought to be tested by RT-PCR.
- The ICMR has underlined that tests are a surveillance tool. The utility of the test was evolving and its value was dependent on field conditions. They were not a replacement for RT-PCR tests.
- However, with the accuracy widely ranging from 5% to 71%, there are questions on whether they can reliably help indicate the spread of the infection.
What do we need right now?
The need of the hour is to have rapidly deployable RT PCR kits.
If we can reduce the time taken for analysis, or have a paper-based strip that can detect the virus, it would be more useful.
What is RT-PCR?
- Real time RT-PCR is a nuclear-derived method for detecting the presence of specific genetic material from any pathogen, including a virus.
- Originally, the method used radioactive isotope markers to detect targeted genetic materials, but subsequent refining has led to the replacement of the isotopic labelling with special markers, most frequently fluorescent dyes.
- With this technique, scientists can see the results almost immediately while the process is still ongoing; conventional RT-PCR only provides results at the end.
- While real time RT-PCR is now the most widely used method for detecting coronaviruses, many countries still need support in setting up and using the technique.