Are there two Novel Coronavirus strains and one strain more virulent?

Are there two Novel Coronavirus strains and one strain more virulent?

Last Reviewed : 12/15/2020
Are there two Novel Coronavirus strains and one strain more virulent?

2019-nCoV or SARS-CoV-2 virus originated in China and was transmitted all over the world. It was initially considered to be a zoonotic disease (a disease that is transmitted from animals to human beings). Within no time, it became apparent that it can spread from humans to humans. Genetically, it is close to coronaviruses that cause previous epidemic – Severe Acute Respiratory Syndrome (SARS-CoV) and Middle East Respiratory Syndrome (MERS-CoV).

A study published in the Journal National Science Review confirmed two types of SARS-CoV-2 virus. Genetic analyses of 103 SARS-CoV-2 genomes demonstrated that these viruses evolved into major types designated as L type and S type. S type is considered as an ancestral version and it is less virulent than the L type. S type prevalence is around 30%. L type, which evolved from the S type, is the more virulent type and its prevalence is around 70%. It transmits faster and replicates faster in human beings. L type was seen in 97% cases in the Wuhan city where this pandemic first started. This study also hypothesized that rapid and aggressive interventions taken by the Chinese government may have led to suppression of L type in Wuhan letting S type to spread more.

Another study by Jamal et al also demonstrated S type and L type SARS-CoV-2 virus. This study also confirmed that L type is a more virulent strain. It is not clear which type is more predominant outside China. The prevalence of these types might have changed as the pandemic exploded all across the globe. It is also not clear if the type of virus is playing any role in higher death rates in countries like Italy and Spain and lower death rates in countries like Germany. More research is needed to identify types of virus in various countries. This may give an idea about the virulence of the virus and how fast it may spread.




  1. Xiaolu Tang et al. On the origin and continuing evolution of SARS-CoV-2. National Science Review, nwaa036,
  2. Jamal et al. Molecular Analyses of Over Hundred Sixty Clinical Isolates of SARS-CoV-2: Insights on Likely Origin, Evolution and Spread, and Possible Intervention. Preprints 2020, 2020030320 (doi: 10.20944/preprints202003.0320.v1).

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