- Of the strains analyzed, each strain had on average about 7 mutations. 
- As of now, the G strain and its Gh and GR descendants are the most common strains in the world. The L and V strains are gradually vanishing.
- The G strain likely has higher fitness and has became the predominant strain because its mutation results in a more stable spike protein. The spike protein is responsible for the initial binding of the virus to the host cell. This leads to a an increased amount of the virus, though there was no indication that it caused increased disease severity. 
- There is currently no evidence that one strain is worse than another.

Characteristics of the Strains

There are at least six known clades that have arose by differential mutation. They are:
- L clade (original one from Wuhan, China)
- S clade
- V clade
- G clade
- GH clade
- GR clade

The following graphic displays the geographic distribution of these strains.
Note: O stands for "other" mutations that are infrequent and currently unproblematic.

Wayne State University

Researchers at the University of Bologna conducted the largest genomic study of SARS-CoV-2 to date, analyzing 48,635 different genomes and their mutations. There are currently six known strains around the world with differential geographic and genomic distribution, though there is little genetic variability between them, which is beneficial because a viable vaccine would likely be effective in fighting all of them.


The Six Strains of COVID-19

Mercatelli, D., & Giorgi, F. M. (2020). Geographic and Genomic Distribution of SARS-CoV-2 Mutations. Frontiers in Microbiology. https://www.frontiersin.org/articles/10.3389/fmicb.2020.01800/full

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