Quoted: Ajay Sethi, associate professor of population health sciences at the University of Wisconsin-Madison, explained that “viruses like SARS-CoV-2 evolve as they replicate in a person with infection and as they spread from one person to the next. When that evolutionary process yields a strain that has a genetic make-up which is very different from the original virus, it is considered a ‘variant.’ ”
He added that “a virus is a ‘variant of concern’ if it has the potential to threaten the pandemic response in some way. It may be more infectious than other variants, cause more severe illness, not be detectable by current tests, less affected by current treatments, partially escape immunity provided by current vaccines, or a combination of these.”