It's less that and more "we just haven't tested it in older populations yet".

Sure you are more likely to have it the older you are but even then you are unlikely to have all the strains. The vaccine covers like 9 or 10 different strains so it can protect you from the other strains even if you already have one of them.

It's generally only when you get into the 60s and up that the justification for not recommending the vaccine changes. Once you get into those later years the immune response changes a bit and you get new concerns.

An example being herpes zoster (chickenpox) where after a certain age you are recommended to get the shingles vaccine instead of the chickenpox vaccine since the way the disease presents and how the body reacts to it changes with age (technically shingles can happen at any age but generally herpes zoster presents as shingles instead of chickenpox the older you get).

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ranma42 4 days ago | parent [-]

> you are recommended to get the shingles vaccine instead of the chickenpox vaccine since the way the disease presents and how the body reacts to it changes with age (technically shingles can happen at any age but generally herpes zoster presents as shingles instead of chickenpox the older you get).

If the underlying virus is the same, what is different between the vaccines? How it presents shouldn't matter as much?

	▲	OneDeuxTriSeiGo 3 days ago \| parent [-]
		> what is different between the vaccines? The shingles vaccine is a larger/more aggressive dose than the chickenpox vaccine. And nowadays chickenpox vaccine uses live attenuated viruses (i.e. modified to be non-infectious but still look the same) whereas the shingles vaccine uses recombinant proteins. This allows the shingles vaccine to deliver the higher viral load that they want for inoculating against shingles without putting a bunch of live viruses into the body. It's also worth noting that the recombinant vaccine is more effective for shingles compared to the equivalent viral load live vaccine by a significant margin. It's something like 90% reduction in incidence vs 50%. ---------- > How it presents shouldn't matter as much? It's not an all or nothing thing but it's a matter of percentages. And the big reason why they present differently is that chickenpox kind of attacks every part of the body since it's new. It of course does best at infecting the skin and nerves but it mildly affects every part of the body. But then it goes dormant in the nerves because that's where it's most "compatible" and the body is the worst at fighting it. So then with shingles your body still has the immunity but the reactivated virus is able to out-compete your immunity in the nerves and it wakes up in whatever specific nerve and spreads along that nerve. This is why shingles generally presents in a band on the body. It's spreading along a specific nerve "line" rather than spreading throughout the whole body, blood, and all. And so the because the infection can't spread broadly throughout your body it ends up concentrated in that location and presumably the higher viral load combined with focusing on the specific proteins rather than the whole virus increases the body's sensitivity to these flair ups, catching them before they can reach momentum. And then that focused immune training sits on top of the body's existing immunity for the initial "whole body" presentation of the virus.