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Indemnity4 t1_isw6q4y wrote

There is already a Leptospirosis vaccine for humans... Several have been available since 1920...

Challenge is there are many different types of leptospiral bacteria and they live in many different animals.

The current top priority is reducing infection in animal reservoirs.

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ConnieHormoneMonster t1_isxwtsu wrote

Piggybacking, how come with things like this and the flu with multiple strains we can't just combine multiple vaccines into one shot to combat multiple strains?

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Ciaobellabee t1_isxy4y8 wrote

So with flu in particular it mutates constantly with old strains becoming less common and new ones we don’t have vaccines for becoming more common each year. That’s why you get regular boosters to get the latest version of the vaccine.

Sadly we can’t predict how it might mutate, and things like flu and covid mutate a lot, so we can’t make a preemptive vaccine.

For viruses that mutate slower (often because they spread slower through populations and/or are very rare), your childhood vaccination is likely to stay effective your whole life.

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ConnieHormoneMonster t1_isxyfjz wrote

Ah that makes more sense.

When they say there's multiple strains but they don't know which one will be dominant this year, it suggests theres like a finite number that remains constant and they're just guessing which one is up this year, rather than the idea of a mutating and evolving virus like we understand Covid to be.

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hwillis t1_iszitw2 wrote

> it suggests theres like a finite number that remains constant and they're just guessing which one is up this year

Close! Influenza is recombinant, meaning different viruses can swap out sections of genome with each other. The huge majority of viruses don't do this, and influenza is the only one that's super infectious.

You know how strains are named stuff like H1N1 or H5N8? H and N refer to the most important surface proteins, and the numbers are the specific variety. Within each variety there are tons and tons of mutation versions. So if you have an H-mutant virus and an N-mutant virus that seem to be doing well on their own, they may combine to become even more infectious. If you have two H-mutants, they are much less likely to suddenly become a problem unless they can find an N-mutation that is more infectious or more dangerous.

Note that they can also recombine with animal (eg pig or bird) strains, not just humans. It's not that it jumps species so much that it can potentially combine two dangerous aspects- the H protein may be dangerous in all species, but the N protein may be holding it back. If it picks up a human-compatible N protein, suddenly we're in trouble. We know this is how a lot of the more recent big waves of influenza happened, like H1N1.

Influenza mutates faster than covid even without recombination, but covid is SO infectious and immunity is still not widespread enough to keep up with mutations that are relatively small. Influenza is battling against centuries of built-up immunity, so it needs to be really lucky to have a sudden change.

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Matir t1_isxyvwg wrote

We do actually have multiple flu strains I'm the vaccine. Most of the vaccines now are Quadrivalent, meaning they have four strains in the one vaccine. The problem is that the flu mutates quite rapidly and there are many subtypes of each of the larger virus clades, and predicting which ones will be most active each season is hard. Scaling is a bit hard because it's essentially making 4 vaccines and packaging them in one syringe, so adding more varieties has linear costs but diminishing returns.

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PartyOperator t1_isytxok wrote

The newer pneumococcal vaccine has 20 strains! Just a lot of different bacteria out there.

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theobromus t1_isxywl6 wrote

Well, for flu we do that - the flu shot you get will target 4 different variants. And the newer covid "bivalent" boosters target 2 covid strains.

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RobertColumbia t1_itbft1k wrote

This is, in fact, done. Many flu vaccines are labeled "quadrivalent", which means that they provide antigens for four different flu strains. Similarly, the new (for Fall 2022) "bivalent" Covid vaccine boosters encode proteins for both the original Wuhan strain and Omicron. Gardasil-9 provides protection against nine different strains of HPV.

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