Next Covid wave, if it hits, may not be deadly: Experts : The recent surge in the number of cases in Delhi has been mainly due to two new sub-variants

PARAG BISWAS, SNS, SILIGURI, 2 MAY, 2022: After a brief sigh of relief, several parts of India are witnessing a steady rise in Covid-19 cases for a couple of weeks now. The sudden surge has led people in north Bengal as in the other parts of the country to wonder if an other try to wonder if an other deadly wave of the coronavirus infection is likely.

However experts in north Bengal believe that it is unlikely that the recent spurt in cases will result in a wave as deadly as the one caused by the Delta variant of Covid-19 during the months from April to June in 2021.Dr Ranadhir Chakraborty, a senior professor of the Department of Biotechnology, University of North Bengal, feels that though there was a looming probability of a fourth wave, it might not turn out to be as perilous as the second wave last year. 

"The recent surge in the number of cases in Delhi has been mainly due to two new sub-variants, namely BA.2.12 and BA.2.10, which have been found in over 60 per cent of the total samples from Delhi, sequenced recently, and are believed to be circulating in Haryana, Uttar Pradesh and Gujarat as well.

In BA.2.12, there are two very significant mutations. The first one is L452Q, which was present in the deadly Delta strain but not in t he earlier BA.2 variant. In the mutation, which has occurred in the receptor binding domain of the coronavirus, Lucin has changed into Glutamin. In the second mutation, namely S704L, which has taken place in the S2 domain of the virus, Serine has changed into Lucin.

The S2 domain is the immunogenic domain of the SARS Cov-2 virus and the antibody target area of the virus.

A mutation in this zone, which is extremely mysterious, means that antibodies may not be able to target the coronavirus and the virus may evade antibodies acquired through vaccination and earlier infection. The mutation has also made the virus 30 percent more infectious than Omicron as it has enhanced the rate of membrane fusion between the host cell and the virus particle leading to a higher transmissibility.

In BA.2.10, there is a key mutation, namely S959P in which Serine has changed into Proline. The mutation has occurred in the ORF lb genetic locus of the SARS Cov-2 genome, which encodes for the replicative enzyme. It means that though BA.2.10 is less infective than BA.2.12, it too can evade the immunity acquired from vaccination and previous infection," said the senior microbiologist, who hoped that the disease caused by the new sub-variants would be less fatal. Dr Chakravorty, however, warned that the recurrence of mutations in the coronavirus was an indication that the covid pandemic was far from being over.

"We are most likely to witness more re-infections and co-infections in the future which might even evade natural, acquired or vaccine induced immunity and render all antiviral drugs and existing therapies absolutely ineffective. It is, therefore, extremely necessary that we continue to follow covid appropriate behavior to prevent a large-scale spread of the disease," he cautioned.