Earlier in this thread, someone wrote in lurid terms of a more virulent L strain having evolved from an older S strain of this current virus.
It might appear, however, that this is an over-interpretation of statistical data:
https://www.livescience.com/coronavirus-mutations.html
Nathan Grubaugh, an epidemiologist at the Yale School of Public Health who was not part of the study, said the authors' conclusions are "pure speculation." For one thing, he said, the mutations the study authors referenced were incredibly small — on the order of a couple of nucleotides, the basic building blocks of genes, he said. (SARS-CoV-2 is about 30,000 nucleotides long).
These slight changes likely wouldn't have a major impact, if any at all, on the functioning of the virus, so it would be "inaccurate" to say that these differences mean there are different strains, he said. In addition, the researchers looked at only 103 cases. "It's a very small sample set of the total virus population," Grubaugh told Live Science. Figuring out the mutations that a virus underwent worldwide takes "a nontrivial amount of effort and sometimes takes years to complete," he said.
Other scientists agree. The finding that the coronavirus mutates into two strains with the L strain leading to more severe disease "is most likely a statistical artifact," Richard Neher, a biologist and physicist at the University of Basel in Switzerland, wrote on Twitter. This statistical effect is probably due to early sampling of the L group in Wuhan, resulting in a "higher apparent" case fatality rates, he wrote.
When there's a rapidly growing local outbreak, scientists quickly sample the virus genomes from patients, resulting in the overrepresentation of some variants of the virus, Neher wrote. The authors of the paper acknowledge that the data in their study is "still very limited" and they need to follow-up with larger data sets to better understand how the virus is evolving, they wrote.
. Much more diplomatic than "who couldn't give a toss"...