There have been many cases across the world where patients tested positive for COVID 19, after being fully recovered from the disease. As a safety measure, some of these patients have been quarantined again. However, the question that arises here is- Why?! Well, Science has an explanation for the same.
As per the guidelines from the World Health Organisation, patients who are clinically recovered ought to test negative for virus twice. A person’s exposure to the novel coronavirus can be detected by two methods – by testing the presence of the virus in the body or by the presence of anti-bodies released by our bodies to fight the virus. The latter test is also termed as a fast or serological test. It is used when it’s been a week to the person being infected by the virus.
This is the time when the body is required to produce anti-bodies. These anti-bodies then show up in our blood samples. Hence, if a person is tested for the antibody test anytime before the gestation period, the higher the chances are that the test results will be negative. The serological tests are mainly useful to conduct tests on a large scale and evaluate the spread of disease in a cluster or community.
The reasons which can be factored in for the patients who test positive after recovering from the disease is that if the sample which is collected has the dead virus. The pathogen cannot be cultured inside the laboratories. However, the test can show the presence in the swab collected for examination; making the patient test negative in the second week of disease and then again test positive later.
On the other hand, Reverse Transcriptase- Polymerase Chain Reaction(RT-PCR) has been recommended by WHO. As per the WHO, RT-PCR is the most commonly used confirmatory test to identify COVID-19 cases. This test enables to read the presence of RNA in the sputum or swab to detect if a patient is a carrier.
To detect the presence of the microbe, the RT-PCR is the more sensitive test because while detecting the virus, the nucleic acid is amplified many times over.
