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yofomojojo t1_jdjj3fe wrote

Reply to comment by PHealthy in What happened to the old COVID variants, like Delta? Could they come back? by number1dork

Just to follow up on the re-emergence question. Here's a fun fact about the original Influenza epidemic we call the Spanish Flu; H1N1: It actually died out, once.

Partially from its own mortality rate, partially from built up immunities over time and evolving variants, but by the time we understood what viruses really were and how to approach them, there was no known surviving sample of it.

Before it died out, though, it passed on, first into the birds as H1N2, swapping out one bit for another, and again into pigs as H3N1, which themselves eventually crossed and produced H3N2, but enough mutations and variations kept the base nodes on infrequent rotation over the years. And eventually they met and hot swapped again, giving us the "Novel" influenza virus we called Swine Flu, H1N1.

And at some point, someone found an inexplicably well preserved vial of blood containing the Spanish Flu from back in the early 1900s, and tested it, confirming suspicions that yes indeed, through a series of exchanged hands, swine flu was a perfect re-assembly of the original Spanish Flu strain of influenza.

Tl;Dr - re-emergence is entirely possible even when the given strain has already gone extinct. Blind mutation and hot swapped component parts can always put Humpty Dumpty back together again.

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im_thatoneguy t1_jdjlrq0 wrote

Out of curiosity if H1N1 Spanish Flu == H1N1 Swine Flu, why was Swine Flu so much less virulent? The Spanish Flu was particularly deadly among younger people and no young people would have been exposed to the extinct Spanish Flu.

(I Had H1N1 and it was awwwwwffullll, but didn't shut the world down like Covid or Spanish Flu).

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EDIT: They're not the same:

>The Centers for Disease Control and Prevention said Friday the swine flu virus appears to be about as contagious as the average seasonal flu. In examining the virus, it also did not find the genes they think made the infamous 1918 flu so deadly.
>
>https://www.npr.org/templates/story/story.php?storyId=103728922

Edit edit:

>Model to Explain the 1918 Mortality Patterns.
>
>Elderly individuals may have been protected from the 1918 virus by childhood exposure to an H1N1-like virus (5). We estimate that H1 and the H2 + H5 lineage diverged from a common ancestor near the time of the 1830 pandemic (SI Appendix, SI Text and Figs. S13 and S14). Moreover, protection was clearly greatest in those born before 1834 (5) (Fig. 3A), implicating the 1830–1833 pandemic virus, which would have primed the majority of that age group. If an H1-like virus emerged in 1830, it would likely have been positioned near one of the orange stars close to the root of the tree in SI Appendix, Fig. S13. Those primed as children between 1830 and 1889 by this HA lineage would likely have had considerable protection against the 1918 HA, comparable to that exhibited during the 2009 H1N1 pandemic by those born before 1957 (32), based on the similar genetic distances separating the childhood and pandemic virus HA in each case

https://www.pnas.org/doi/10.1073/pnas.1324197111#supplementary-materials

The tree here would indicate that H1N1 like Covid just continued to evolve and become endemic, it didn't die out. Nowhere is it claimed that the genomes are the same. In fact as the CDC mentions, we had a full sequence by 2005 of the 1918 flu and it didn't match.

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hayalci t1_jdjswfg wrote

In addition to r/brown_felt_hat's answer, Spanish Flu was around World War I, ravaged economies, poverty, illness, and a general lack of resources probably would have confounded its effects.

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brown_felt_hat t1_jdjn0u2 wrote

We are definitely a lot better at recognizing and treating illnesses these days. We have drugs to mitigate infection vectors (eg cough syrup prevents coughing, a massive transmission vector, decongestants limit mucus production so you're not sneezing snot everywhere), we have drugs to treat dangerous symptoms (anti pyretic drugs to prevent high fevers, repository drugs to prevent failure), and just much better overall awareness of how viral infections work and spread.

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im_thatoneguy t1_jdjx0hg wrote

So if you didn't take any medication, you had pretty much the experience you would have in 1918--except you would probably take Paracetamol for fever and if your condition worsened you could receive tamiflu and other stronger medications?

Or like the difference between Alpha and Delta Omicron, they're the "same" but probably exhibited substantially different mortality?

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Atechiman t1_jdk1y5e wrote

HXNX is a way of indentfying large families of Orthomyxoviridae in particular alphainfluenza betainfluenza gammainfluenza and deltainfluenza, the four 'families' of bird/mammalian flus (often just called a,b,c,d) I forget off hand the exact proteins it refers to, but all of the viruses have one of four of them so H1N3 viruses tend to behave similar to each other but different from H1N2.

H1N1 is an alpha virus, that different strains have caused several major pandemics including the Swine Flu. It is an avian virus usually, but some strains are endemic in humans and it is often the flu-a vaccine for a year.

1918 flu is an outlier as was the '83? '82? Russian pandemic novel. The 2008 was slightly more lethal than normal but not more contagious.

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byerss t1_jdjw4rg wrote

H1N1/09 did hit younger people harder than older folks. I remember reading that one theory was that for 2009 older folks may have had more natural immunity because they were exposed to flu variants based on Spanish Flu.

Look up the death vs age graphs for swine flu.

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yofomojojo t1_jdk0chr wrote

Re: your edit - I'm open to being rebutted here but, I think that clip might be a bit outdated. H1N1 is Swine Flu and Spanish Flu. If we're doing podcast links, RadioLab covered this topic again during early Covid. Current scientific papers and articles on the topic all seem to understand and accept that H1N1 is the virus in question in both cases.

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im_thatoneguy t1_jdk1ror wrote

https://pubag.nal.usda.gov/download/26795/PDF

That radiolab is discussing the basis of a 2005 paper which included the entire genome. So a 2009 CDC analysis (which NPR cites) should be based on the fully sequenced H1N1-1918 genome from 2005.

Edit:

https://www.pnas.org/doi/10.1073/pnas.1324197111#supplementary-materials

This states that H1N1 didn't go away, it continued to evolve into a seasonal H1N1. And that likely the 1918 H1N1 branched off into the H1N1 in pigs prior to the human outbreak.

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jinxjar t1_jdk7b1k wrote

it's like that time when i did the math problem wrongly but got the correct result.

i failed that test, but H1N1 passes.

no fair

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