DNA Explainer: How the new COVID-19 variant is fooling RT-PCR tests - all you need to know

As the country battles with the fresh and more powerful wave of the COVID-19 virus, there is something else that is even more alarming. Some reports suggest that now the novel coronavirus is fooling the RT-PCR testing method which is considered the most authentic of all. 

Of late it has been seen that many patients were found COVID-19 negative in the early stages when they got the RT-PCR test done when symptoms like cough, fever or shortness of breathe surfaced. However, when their condition did not improve and they got another test done, this time they were tested positive for the COVID-19 virus.

We all can understand what a false test result can lead to. When a COVID-19 positive patient comes negative in the RT-PCR test, it is not just the patient but everyone who comes in contact with him is at high risk.

The patient does not consult the doctor leading to his/her condition getting deteriorated in the process. Not just that, the patient might become a super spreader of the virus unknowingly to all the people who come in contact. 

Why the RT-PCR test is failing?

The biggest reason is that the virus they were designed to detect has changed its look and behaviour considerably since the last year.

RT-PCR tests usually look for more than one part of the coronavirus.

But the presence of SARS-CoV-2 genetic variants in a patient sample can potentially change the performance of the test.

Inadequate sampling, improper transport, and late swabs may miss COVID-19 virus in RT-PCR tests, say some experts. 

Some are of the opinion that the virus did not colonise the nasal or throat cavity due to which swab samples taken from these areas didn't yield a positive result.

Some test kits now come with a disclaimer that it may not be able to detect the virus in all cases.

How RT-PCR test is done

The Curative SARS-Cov-2 Assay is a real-time RT-PCR test used to detect SARS-CoV-2, the virus that causes COVID-19. This test is authorized for prescription-only use. 

The test is performed by collecting a throat swab, nasopharyngeal swab, nasal swab, or oral fluid specimen from an individual suspected of COVID-19 by doctors.

What FDA has to say

The US Food and Drug Administration is alerting patients and health care providers of the risk of false results.

FDA is alerting particularly regarding the false-negative results, with the Curative SARS-Cov-2 test.

Risks to a patient of a false negative result include delayed or lack of supportive treatment.

It could also mean a lack of monitoring of infected individuals and their household or other close contacts for symptoms.

This could result in an increased risk of the spread of the COVID-19 virus within the community, or other unintended adverse events.