COVID-19: Indian Council of Medical Research (ICMR), which is the nodal agency tackling COVID-19, on Thursday issued an advisory regarding the use of serological or blood tests in the hotspots of COVID-19 outbreak, but the advisory was pulled down hours later.
Coronavirus Pandemic: As the COVID-19 cases in India are on a rapid rise, various states have started to look for blood-based rapid tests instead of the currently used swab tests which take longer to give out the results. So far, Kerala has already started the use of these tests, while Maharashtra seems to be set to roll them out. Moreover, Chhattisgarh has sought permission to switch to these tests, according to an IE report.
The IE report also stated that the Indian Council of Medical Research (ICMR), which is the nodal agency tackling COVID-19, on Thursday issued an advisory regarding the use of serological or blood tests in the hotspots of COVID-19 outbreak, but the advisory was pulled down hours later. At present, India has around 20 hotspots.
Coronavirus outbreak: What are serological tests?
The IE report, quoting Johns Hopkins Bloomberg School of Public Health, stated that serology tests are blood-bases tests which help in identifying whether the individual has been exposed to a certain pathogen. These tests analyse the entire blood’s serum component, which includes antigens – the antibodies to specific components of pathogens. The human body’s immune system recognizes the antigens as foreign components and targets them.
Blood contains a matrix called plasma as well as blood cells. If the components of whole blood which cause it to clot are removed from the plasma, the remaining component is the serum.
How are serological tests different from the tests conducted presently?
The tests which are being widely conducted to test the presence of SARS-CoV-2, which is the coronavirus causing the COVID-19 infection, are known as Polymerase Chain Reaction (PCR). In the PCR test, the nasal or throat swab of the individual is collected and, from the sample, the RNA of the patient is extracted and converted into DNA. The DNA is then checked for the presence of the virus. The PCR test takes about nine hours to produce results, because the test includes two stages – the first requiring a screening to check the family of the virus and the second to confirm if the virus is indeed SARS-Cov-2, the report said.
The report further said that the serological tests, which screen the plasma for antibodies developed in the body to protect it from the virus, takes under 30 minutes to give out results. However, the serological tests can only be conducted after several days of the infection first having occurred in the individual as the antibodies take a few days to form. In this regard, PCR test can detect the presence of the virus at an earlier stage. Moreover, even once the serological test has been conducted, the positive people will have to go through the PCR test.
What did the ICMR advisory say?
The interim advisory issued by the ICMR regarding the serological tests on Thursday stated that the people living in the hotspots should be tested for the presence of COVID-19 using rapid tests and those who are found to be antibody positive should undergo PCR test to confirm the presence of SARS-CoV-2. Those who are found to be antibody negative should be quarantined at home, the IE report quoting the advisory said.