Hyderabad-based Centre for Cellular and Molecular Biology (CCMB) is at the forefront in studying the different variants of the Sar-Cov-2. The institution conducts genome sequencing to understand the nature of the variants and its properties.
Talking to NewsMeter, Director of CCMB Dr. Rakesh Mishra discussed the double mutant, triple mutant, and the third wave India is yet to witness. Excerpts:
What is a double mutant?
B.1.617 (double mutant) was first sampled in early October 2020 in Maharashtra. This lineage is characterized by about 15 mutations all over its genome. 6 out of the 15 mutations are present in its Spike protein, out of which two mutations, in particular, were of interest: L452R and E484Q. These were of interest because L452R was seen in a variant circulating in California, and was shown to increase the infectivity of the virus, and E484Q was shown in vitro experiments to be an immune escape mutation (possesses the ability to bypass host immunity, either acquired by previous SARS-CoV-2 infection or conferred by vaccination). Because these two mutations were repeatedly mentioned when talking about this lineage, the colloquial name of double mutant came about.
What's the "triple mutant"?
The strain which various news articles and others are referring to as "triple mutant" is a sub-lineage of B.1.617, with an extra mutation in its Spike protein: V382L. The mutation V382L has previously been reported in the US as a low-frequency mutation with possible immune escape properties as seen in vitro assays.
There is no conclusive evidence at this point that associates any of these lineages with a more severe or lethal outcome of COVID19.
Since their footprints are increasing, it is reasonable to think that these are more efficient in spreading.
We have seen that B.1.617 is not resistant to a vaccine or prior infection mediates the immune response.
Which mutant has hit India in second wave?
Unlike northern India where the UK variant is responsible for a high percentage of COVID cases during the COVID Second wave, South India has a different story. The B.1.617 variant known as the 'double mutant' is prominent in Maharashtra and now making headway in Karnataka.
However, what is of concern currently is that the variants spreading in larger parts of the country. The Triple mutant is currently limited to Maharashtra and scientists need more data to conduct genome sequencing to understand the nature of the mutant.
What about South India?
The N440K variant has found be to more dominant in Telangana, Andhra Pradesh, Karnataka, and Kerala.
Is the RTPCR test unable to detect the new variants resulting in false-negative reports?
It is pertinent to note that thousands of cases reported in the recent are results from the RTPCR test. None of the variants can evade its presence, although it is important to know that sensitivity of RT-PCR tests is 70-80%. In certain cases based on the viral load, it may not be detected however it is in the majority of the cases it has. False-negative is expected in few tests among hundreds.
Will May and June see another peak?
All the models currently predict that the COVID curve will hit a peak during May 2nd and 3rd week. However, the possibility is that the caseloads will drop sharply. Models have also predicted that there could be another peak after June but of a smaller intensity, but citizens have to take due care.
The models are calculated based on the present caseloads put out by the government. Currently, the country is reporting 3-4 lakh new cases. During the peak, it may go to 5-10 lakhs range as well, this is minus the unreported cases. We cannot predict exactly due to the poor data availability. If the data on fresh COVID cases is not very good and do not match to ground reality, models are likely to be inaccurate as they are based on such numbers. With eyes closed, one will not know what is elephant if they touch only the tail of an elephant and assume that it may be like a snake.
Less data (COVID number) results in wrong models leading to the wrong prediction. However, we can guess that the caseloads will touch the highest in the mid of May and then drop down sharply.
What about the third wave?
The third wave will be delayed however could be much smaller ( less intensity) given that a large number of the population will be vaccinated by then. It also depends on how the public adheres to guidelines.