GUWAHATI, May 20 - The same L-type strain of the novel coronavirus � which has its lineage to Wuhan in China � is dominant in Assam, studies have revealed.
�Two strains were observed in the first three cases of COVID-19 in Kerala � the S-type and L-type. However, later it was observed that L-type was dominant across the country as has been the case across the globe,� Dr B Borkakoty of Regional Medical Research Centre, Lahowal said.
He further said that scientists are now grouping the SARS-CoV-2 into different clades and subclades each dominant within specific geographical regions.
The L-type strain was considered to be prevalent during the early stages of the outbreak in Wuhan and was considered to be more aggressive and contagious. However, later studies did not document any such aggressiveness of this strain. The S-type, which is evolutionarily older, is being slowly replaced by the L-type or the Clade G which has high transmissibility.
In January, the prevalence of the S-type strain was around 36 per cent of the cases. However, its dominance went on waning after that, Dr Borkakoty said.
In April, the Lahowal-based RMRC had developed a TSP-PCR based test which can detect the L-type and the S-type strains of the novel coronavirus in three hours and found that the Assam strains are of L-type.
Though the coronavirus strain in India has undergone some mutation while spreading within the country over the last few months, the difference in the strain has been found to be less than 0.1 per cent which is not �significant�.
Mutation of a virus happens when it is replicating. Viruses survive through mutation and this is a random act, rather than a deliberate act of survival. �Despite the minor mutation so far, the virulence of the strain has not changed,� he added.
Assam has registered some 170 cases so far and, according to doctors, 90 per cent of them are asymptomatic. �While they are not symptomatic, the patients are getting cured by themselves. However, that does not mean we should lower the guard. People need to be careful as it has proved fatal for persons with co-morbidity,� he added.