Mutations: A new life? The emergence of SARS-CoV2

[drishtantmkawale (Drishtant Maruti)]

Covid 19 new strain

As mentioned by Drishant, certain mutations have emerged independently in other countries but didn’t gain prominence. Though, both the ‘B.1.1.7 UK variants & B.1.351 South Africa Variant’ represent unique combinations of mutations / deletions that have rarely been observed before, scientists speculate that the two lineages may have acquired those during a persistent infection in an immunocompromised patient. Treatment by convalescent serum (or mono- / polyclonal antibody therapies) might have …

In the past 3 months (and even now), we have been seeing that new strains of the SARS-CoV are (re)emerging.
Why is it that these strains are emerging all of a sudden?
This (alongwith few other) question(s) come in my mind when I hear about new strains!
I am pretty sure that the possible answer or even something close to the answer will be interesting to know.

Why didn’t the CoronaViruses that broke out in 2003 as SARS-CoV and in 2012 as MERS-CoV continue for so long…?
Even though SARS-CoV2 has a better affinity towards the ACE2 (angiotensin-converting enzyme 2) receptor and now too it is mutating and is on the verge of creating a new phenotype, why didn’t it happen with the viruses that emerged earlier?