NOTE: Before the virus was isolated (by only one lab in Wuhan) the disease was called COVID-19. When the virus was isolated it was named SARS-COV-2, sometimes called SARS-nCOV-2. The virus SARS-COV-2 causes the disease COVID-19.
Summary: There are 278 strains and 65,000 variants of SARS-COV-2.
A clade is a term for a group of organisms that all originate from a common ancestor, and is widely used in biology. Using phylogeny, which is the evolutionary history of a group of organisms, the development of changes in a set of descendant organisms can be tracked.
In virology, a clade describes groups of similar viruses based on their genetic sequences, and changes in those viruses can also be tracked using phylogeny. Rapid genome sequencing is the method by which developments in a virus’s genomic makeup can be tracked.
SARS-CoV-2 is itself a clade within the family coronaviridae and the genus betacoronavirus. Generally, the genetic variations of a virus are grouped into clades, which can also be called subtypes, genotypes, or groups.
The [WHO] investigation/bulletin included 10,022 SARS-CoV-2 genomes from 68 different countries. In total, WHO detected 65,776 variants and 5,775 distinct variants…
https://www.news-medical.net/health/Viral-Clades-of-SARS-CoV-2.aspx
So what is a virus strain?
When naming life we most commonly see 2 parts: a genus, then species. The species is sometimes broken down into a “strain”. The “clade” is usually a subdivision of the species or subspecies and sometimes a subdivision of a strain. In “Homo Sapiens” the genus is “Homo”, the species is “sapiens”. A clade is used to mean a genetic change that has no meaningful change. I.e. the genes are technically different but the function of the virus is not materially different. (Source: https://www.galaxydx.com/what-are-subspecies-strains-and-clades-in-viruses-and-bacteria/ )
The image below shows both strains and clades of SARS-COV-2.
Links for more information
- Viral clades of SARS-COV-2. https://www.news-medical.net/health/Viral-Clades-of-SARS-CoV-2.aspx
- WHO bulletin “Variant analysis of SARS-CoV-2 genomes”. https://www.who.int/bulletin/volumes/98/7/20-253591/en/
- What are subspecies, strains, and clades in viruses and bacteria? https://www.galaxydx.com/what-are-subspecies-strains-and-clades-in-viruses-and-bacteria/
- Modeling viral clades improves prediction of COVID-19 growth rates. https://www.news-medical.net/news/20201004/Modeling-viral-clades-improves-prediction-of-COVID-19-growth-rates.aspx (This is a good link for more COVID-19 research.) This link has a world map showing which clades are most prominent in each country.
