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iayork t1_jdnxp9k wrote

Despite what everyone is going to say, this has nothing to do with antigenic drift in flu (i.e. accumulated mutations in circulating viruses) and certainly nothing to do with antigenic shift (genome segment rearrangement).

While antigenic drift is a concern and shift is a much rarer concern, the fact is that influenza vaccine immunity wanes extremely fast regardless of shift or drift. This is very well known and there are literally hundreds of publications about it; you can start with Waning of Measured Influenza Vaccine Effectiveness Over Time or Waning Vaccine Effectiveness Against Influenza-Associated Hospitalizations Among Adults, 2015-2016 to 2018-2019, United States Hospitalized Adult Influenza Vaccine Effectiveness Network or many others.

This waning with the influenza vaccine is generally much worse than most vaccines and in particular it’s much worse than tetanus vaccine. The sad truth, though, is we don’t know why immunity wanes so fast. Part of it is that the conventional inactivated influenza vaccine, which has no adjuvant, is poorly immunogenic - but that’s kind of going in circles because “poorly immunogenic” means its immunity wanes rapidly.

Even many more modern influenza vaccines, made through different approaches, are weakly immunogenic and have rapid waning of immunity. So maybe there’s something specific about influenza, that means it has adapted to be poorly immunogenic in people. If so, we don’t have a clear idea what it is.

Including adjuvants with the vaccine does help, and that’s used in the elderly.

But in a sense, it’s not a critical problem now because even if immunity didn’t wane, we’d still need to give nearly annual vaccines because of the antigenic drift problem. It’s annoying, it does mean that people vaccinated in fall are already less well protected by spring, but by summer flu has mostly gone away and mostly you need a new vaccination by fall again anyway.

If and when new vaccines against flu are introduced, with broader reactivity, that don’t need to be modified every year - then this will need to be solved too. But they’re not out yet.

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jawshoeaw t1_jdo97ah wrote

It may be a little of both as the saying goes. Studies of vaccine antibody persistence in a few diseases suggest that if you’re not regularly exposed to the organism in question, the antibodies fade faster, sometimes much faster than in communities where the organism is endemic. Even though the people are not getting reinfected at least not obviously. So (and this is just my idle speculation) since influenza famously does as you said , drift , maybe we don’t get the benefit of reawakening the vaccine with repeated exposure. But back to actual science: it remains a mystery why influenza vaccines fade so incredibly fast , sometimes within a month it’s starting to fade.

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iayork t1_jdqx141 wrote

> if you’re not regularly exposed to the organism in question, the antibodies fade faster, sometimes much faster than in communities where the organism is endemic.

Do you have a recent reference for this? My impression is that that was a good working hypothesis, but it hasn’t held up very well to data - in particular, I think that measles vaccine immunity holds up well even in regions where measles is essentially eradicated.

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RuleRepresentative94 t1_jdpgj0o wrote

Thank you. Really tired of people not understanding that permanent immunity is a property of our immune system, not the virus.

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