RT-PCR test report may be negative when patients go for testing late with high symptoms: Expert

New Delhi [India], April 22 (ANI): If people with symptoms go for RT-PCR test late, after seven-eight days when symptoms become high, then there is a possibility of the test report coming negative, said the director, Institute of Genomics and Integrated Biology, New Delhi.
Amid rumours that new mutants of COVID are behind the false-negative reports of RT-PCR tests of infected patients, Dr Anurag Agarwal, Director, Institute of Genomics and Integrated Biology, New Delhi said, "These double mutants were sequenced only from the samples that had positive PCR reports. So there is no possibility that this mutant cannot be detected through the PCR test. Nothing can escape the double gene. People should know the PCR's sensitivity is 70 per cent."
"If people go for the test late, after seven-eight days when symptoms are high, there is a possibility of PCR (polymerase chain reaction) test coming negative but positive in CT (cycle threshold). This not about a new strain. It is the general behaviour of any virus. When people go for a test late, then many times PCR test comes negative in the nose and mouth. It is because the virus goes deeper inside the body," he explained.
Dr Agarwal said, "People are in a panic because they reach for a test late. Fundamentally, the sensitivity of PCR never goes beyond 70 to 80 per cent. When you take all patients coming at all different stages there is nothing new. It is not because of the mutant strain of a virus."
There are speculations that the mutant strain is behind the recent upsurge in COVID cases in India.
On this, Professor Dr Saumitra Das of Indian Institute of Science, Bengaluru said, "The emergence of a new mutant is a long procedure. I do not think the emergence of new mutant can be correlated with changes in public behaviour like following the COVID guidelines or having strict quarantine rules."
"So far to our knowledge, I do not know whether we can strictly say this has anything to do with the severity or the treatment regimen with this. People have to be careful. We should see how frequently these new mutations are coming out. These are two different issues that we should handle independently," he added.
Dr Sujeet K Singh, Director National Centre for Disease said, "We are having a surge. We are having severity somewhere. We are having high mortality somewhere. But whether it is directly correlated with the mutants we are observing needs to be defined in a statistically valid manner."
Dr Singh said laxity in people's behaviour was behind the spike in COVID cases in the country.
"We are just having a casual correlation of the number of samples sequence in one lab and then trying to see the surge in a particular district or that particular state may not be the right thing. It is not the mutant alone that can contribute to the surge. Our laxity in COVID appropriate behaviour, our laxity in many other majors which are being planned have contributed to a significant level. The mutant could be a very, very small part of it," stated Dr Singh.
There are news reports suggesting that research on double mutant was not conducted even though it was detected in October last year and now it is suspected to be behind the upsurge in COVID-19 cases in India.
On this, Dr Agarwal said, "First such sequence was part of database pack in October. But in October with declining cases there was no knowledge about this particular mutation being important. Nobody except an 'antaryami' person could have possibly thought this was important."
"The outbreak started in December-January in the states of Kerala and Maharashtra. We gave importance to these states and started looking for mutations in these areas. Kerala had the most severe outbreak at that time. This mutation was absolutely not seen in Kerala. So it was not related to the clinical outbreaks over there," he said.
"In Maharashtra, you will see the first report in India of sequences starting to show this came from BJMC Hospital and a few samples were sequenced. But those were not representative. Around the same time, this mutation turned out to be important with papers coming out from California. They tied it with outbreaks. At that point, you have an outbreak. You have mutations available in sequences. And, you have reason to correlate together. We are exactly making the same judgement today. Today we can see many doctors are having breakthroughs. We are correlating that," emphasised Dr Agarwal.
"All these are things that are actually happening in India as well. It has to be seen what is the percentage of vaccinated doctors being infected. We can see most doctors who have breakthrough vaccinations tend to have some kind of escape variants or the other, not the normal strain. It is a good sign of the quality of the vaccination programme. Most of them are having mild illnesses. Especially in India, it is not the only variant. In North India, Punjab does not have it. Kerala does not have it. They also have outbreaks. So it is not a simple single-story," he said.
More than 3 lakh new COVID-19 cases and over 2,000 deaths were reported in India on Thursday, a record-high since the pandemic broke out last year.
According to the Union Health Ministry, as many as 3,14,835 new COVID-19 cases and 2,104 deaths were reported in the last 24 hours taking the total cases to 1,59,30,965, including 22,91,428 active cases.
The death toll due to COVID stands at 1,84,657. (ANI)