Originally Posted by
SHVC
This is becoming a bit of a joke! Lambda more contagious than delta, delta more contagious than beta.
It's not 'a joke' rather it is simply how mutant strains emerge and become prevalent enough to make it into a sizeable enough proportion of the population to become noticeable.
Given the current pandemic spread of the coronavirus mutations are likely bobbing up frequently. However, in order for any of the new variants to 'succeed' enough to be noticed they need to be doing something 'better' than the current dominant variant. Transmissibility and virulence are two ways of succeeding. You will rarely if ever see less successful - that is less transmissible or less virulent - mutated variants outside of laboratories.
A couple of blokes - Darwin and Wallace - wrote about this sort of thing some time back.