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Message: [QUOTE="JustbrewitMan, post: 3480829, member: 7806"] [B]Are there two epidemic strains (one highly-virulent, one designed to stop the spread, a.k.a the "pj theory")?[/B] At this point, [B][U]there is no strong evidence to support this contention.[/U][/B] (1.) As of 3/15/2020, there have been almost 500 genomes sequenced from samples obtained around the world with the evolving spread of the COVID-19 epidemic: [URL unfurl="true"]https://nextstrain.org/ncov[/URL] There is definitely some small genetic variation amongst these strains, but given the known mutational frequency characteristics of coronaviruses during replication as well as their known ability to do recombination (combining sections of two "parents" genetic materials to form a new progeny), it is well within the expected ranges of "genetic drift" and there is nothing to suggest that, so far, it is any more different that what is observed from the spread of the original SARS events 2002-2003 or the yearly influenzae spread. Although I cannot definitively rule out that there [B][I]may [/I][/B]be some important rare mutations that could have occurred so far that made certain strains less or more virulent (due to things like single-point mutations in the right regions of the genome that could then decrease or increase its binding to the human ACE2 cell receptor (needed as a first-step to human cell invasion), or do something like increase other enzymes that could increase its virulence, I could find no evidence so far from experts that indicate that some of these mutations have been documented in the strain variants. But I'll be continually monitoring this! For further reading for those so inclined, there are a couple of discussions from experts at the two links below that argue (convincingly) that the "[I]...recent paper [that] has claimed that SARS-CoV-2 has split into two strains, “L” and “S”, with the “L” strain causing a more severe version of COVID-19. This theory was used to try to explain the higher case fatality ratio that has been seen in Wuhan, China, the epicenter of the outbreak as compared to other parts of China[/I]." - is inaccurate. [URL unfurl="true"]http://virological.org/t/response-to-on-the-origin-and-continuing-evolution-of-sars-cov-2/418[/URL] [MEDIA=twitter]1235217967727681536[/MEDIA] (2) As the pandemic has evolved, it has become clear that the [B][I]mortality observed has also evolved over time[/I][/B]. For example, in Wuhan, the mortality for people who became symptomatic from December 2019 through January 10th was ~15%. From 1/11-1/20 it was 6%, 1/21-31 it was 2%, and its been 1% since February 1st: [ATTACH type="full"]52022[/ATTACH] [URL unfurl="true"]https://www.npr.org/sections/goatsandsoda/2020/03/03/809904660/why-the-death-rate-from-coronavirus-is-plunging-in-china[/URL] The [B]VAST [/B]majority of deaths were in the early phase of the epidemic...when healthcare providers were woefully unaware of what it was, how it was transmitted, how to diagnose it properly, how to provide care, and there were significant delays in care due to the overwhelmed healthcare facilities. Since the identification that COVID-19 is caused by a SARS coronoavirus, things have dramatically gone in a positive direction wrt clinical management of infected patients. The very low mortalities in MANY areas of the world that were the later countries to see COVID-19 (and thus, could have appropriate measures in place early on in the disease spread) support this fairly logical concept. We've witnessed the same thing happen in other countries like Italy, Iran, etc. with high initial mortality rates. 3.) As mentioned by [USER=1329]@auror[/USER] , morbidity and mortality is MULTIFACTORIAL and research is rapidly being published to provide some insights. [LIST] [*]Some factors are patient-specific (like comorbid illnesses, genetic and/or comorbid factors that could make them more susceptible to infection via variation in cell-surface ACE2 amounts (male>female, smokers>non-smokers, active hypertension>no hypertension, perhaps race, etc.) [*]Some factors are public-health related (quarantine effectiveness for positive cases, social distancing measure implementation time and amounts, numbers of hospital beds and types of equipment available) [/LIST] EVERYONE please continue to be safe, patient, try not to over-react/panic, do healthy things, go enjoy a nice walk outside today (going to be a really nice day!). Best, JBM [/QUOTE]

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