Are there two types of COVID-19 viruses?

As per the study, one of these strains is more aggressive than the other, and was associated with 70 per cent of the analysed strains. The researchers have also said that the prevalence of the more aggressive strain decreased after January 2020.

Within the 103 genomes, one of the two strains of the SARS-CoV-2 was more prevalent. The researchers have called the two strains ‘L’ and ‘S’ types.

Further, the researchers maintain that while the L type was prevalent in over 70 per cent of the cases analysed, the S type of the virus is the ancestral version, which means that the L type is derived from the S type and it transmits and replicates faster in human populations, researchers conclude. Because of this higher transmission rate, the L type is considered to be more aggressive.

Significantly, of the 27 viruses out of 103 isolated by the researchers that were from Wuhan, 26 were L type (96.3 per cent). Among the 73 viruses isolated from outside Wuhan, 45 were L type (61.6 per cent) and 28 were S type.

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