They're typically mild infections, but some cats can be chronically infected. In those cats, a mutation in part of a specific gene can cause FIP.

Yes, and no.

It is less severe because everyone has some kind of immunity to it. The virus inherently is probably still as virulent as the original type to someone with zero immunity.

Wrong.

It doesn't matter if the host dies or not, all that matters is that it can spread before the host dies. COVID was perfectly capable of doing this via asymptomatic spread. (see: Delta).

Omicron outcompeted Delta because it had mutated so wildly that it could bypass all the antibodies the vaccines had generated up to that point, plus it drastically reduced the incubation time, meaning more spread potential. That's it. It could've been as lethal as Delta and would've still been successful.

Omicron is likely as severe as the original strain, the difference is now everyone has some kind of immunity to it, so it wasn't killing people nearly as much on a per-person basis.

> Very cool write up, especially learning how viruses tend to become less lethal and more contagious.

They don't. It's a myth that continues to be propagated because it sounds logical to the layman. It is our immunity that makes them less lethal (when we survive).

If viruses behaved this way as a given, we wouldn't have been getting killed by smallpox and many other viruses for millennia.

I never knew that! I just read that it can turn fatal due to a mutation, but do these spread in cats like COVID variants? Omicron and Delta already demonstrated that outcompeted variants can come back far worse.

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There is also a loss of fear. An animal that would normally hide or run away from you, may approach you. This can lead to a biting incident. If you brain damaged an animal with drugs, gave it a sore throat, and gave it stimulants, would it behave the same way?

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The numbers aren't representative though because very few are testing now and being logged

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You should still get the bivalent booster now if you can. In the US, it is based off of BA.5, which isn't too far removed from the current circulating XBB 1.5 and BQ1.1 strains.

It is likely that later this year we'll get an updated booster again, possibly targeting XBB if it still sticks around.

> The natural life cycle of any virus is for it to become more infectious and less dangerous to the hosts since that's the best way for the virus to survive.

This is a myth that gets repeated too often. Viruses sometimes become less deadly, sometimes more deadly. And many remained as lethal as always.

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Similar thing happens in cats with FIP, another coronavirus.

They also continue to exist in chronically infected people, mutating over the course of infections that could last years(or decades?)

These are 3 Delta variants detected this January, one of which was up to 90 mutations(and probably still mutating):
https://twitter.com/LongDesertTrain/status/1624464486596849670

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Non-Omicron variants like Delta are only extinct in the sense that they are no longer widespread in the general population. Even so, they continue to mutate in chronically infected people for years, resulting in variants that make even Omicron look "pedestrian." https://www.nature.com/articles/d41586-022-02996-y

Here are three Delta variants detected this January, one of which got up to over 90 mutations: https://twitter.com/LongDesertTrain/status/1624464486596849670

This might be how Omicron started and how the next big variant emerges.

Even if we did, life would, uh, find a way.

So what we need is a new strain of covid that can squeeze out the others but which we can easily cure, that's what you're saying

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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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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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.