COVID-19 Testing – Are we on the right track with antibody tests?
The latest figures in India of confirmed cases has reached 42,700 with close to 23,500 being active and 1400 deceased.
The Indian Council of Medical Research (ICMR) had advised the states to use antibody testing for rounding up the positive cases in tackling the COVID-19 fight in India. But over time it has been substantiated that it is not the most reliable test and to shift to RT-PCR (real time Reverse transcriptase – polymerase chain reaction) as the focus of testing and diagnosis of COVID-19. The rapid testing antibody kits that are being used by States are fanning out unreliable results.
Why is RT-PCR being considered over Rapid Antibody Testing?
Rapid antibody testing or serological tests is the more traditional but rapid way of testing the antibodies in body against the virus. But the reliability of these tests is under scrutiny with many false negative and false positive cases coming to light. The problem lies with the basics+ of these tests. The antibody tests are based on the presence of antibodies, which can appear in the blood from 7-28 days of contracting the infection, during which the patient is infectious. This puts the purpose of testing in haystack.
On the contrary, RT-PCR is a more reliable test wherein the test sample is throat or nasal swab. The sample is tested for virus RNA structure. If the genetic sequencing of this RNA matches that of SARS-COV-2 virus the test is sure shot positive for COVID-19. This is definitely more sensitive test as compared to the rapid antibody test where a positive result appears even if the patient has antibodies of Influenza virus which causes common cold.
So, why are the RT-PCR tests in scarcity and not being used in place of antibody tests?
The logistics play a major role here. With the chemicals used for RT-PCR tests and the specialized laboratories and trained clinicians and pathologists required, the logistic expense sky rockets. Moreover, these tests need to be in a sample group of 30 minimum to be processed for more effective utilization of the kits. This means more processing time. But the rapid antibody tests are more user friendly with no specialized training required and can be done on-site with rapid results.
The antibody tests are evidently not detecting the virus but can be useful in determining the infection magnitude and range in a community. This information can come in handy in case the governments decide to lax the lockdown protocols in areas in coming days.
According to Dr. Harsh Vardhan, the Heath Minister, India will be having the kits that are made in country by the end of May. This is a good news in country’s fight against COVID-19 with quality checked kits in use and logistic expenses in check for a more widespread testing across the country.