During college I faithfully got my flu vaccine every year. Shortly after I left college the US had a year with a bad flu vaccine shortage (2004).

When discussing the shortage with my coworkers at the time (who grew up in a different part of the country than I did), they replied that they didn't ever get the flu vaccine because they were told that if they ever had to skip a year (such as the year there were shortages) they would give much sicker than if they had never gotten the flu vaccine.

Is there any scientific truth to this belief?


I've worked on influenza in the past, and I've never heard that particular justification for missing a flu vaccine before. I confess I can't even find it when I Google for that particular belief.

There are some viral diseases where it's true that prior vaccination (or natural exposure) may cause a severe overreaction of the immune system that results in more severe disease. However, the only common one I know of is Dengue fever, where exposure to one strain makes infections from other strains much more severe.

Were your friend's belief be true, all vaccines that miss a strain (which are functionally similar to not being vaccinated) would be serious problems for the next year, because everyone would be in the position you're describing - immunologically having missed a vaccine - and there's no evidence I can find of that, and absolutely no mention of it in most influenza vaccination guidelines.

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    "That's just not what flu does" isn't really a good answer that meets our standards here (explanation, citation, etc). Can you be more specific? – Zaralynda Apr 15 '15 at 12:02
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    @Zaralynda To be blunt, that notion is also why I don't post on skeptics. I'm an infectious disease epidemiologist, I work on influenza, and to be frank, with NIAID paylines at <10%, people aren't running studies for things that aren't a concern. It's going to be extremely hard to find a reference proving a negative, and it definitely exceeds the level of effort I'm willing to put into disproving some friend's random assertions about a virus. – Fomite Apr 15 '15 at 15:50
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    it seems like an answer that explains that the flu vaccine covers different strains every year and that doesn't change its effectiveness (you either catch one you're vaccinated against or one you aren't) would be an answer, but I'm not a medical professional – Zaralynda Apr 15 '15 at 15:58
  • @Zaralynda Beyond that, I have provided an explanation: If that were true, flu would look like dengue, and it doesn't look like dengue. – Fomite Apr 15 '15 at 15:58
  • @Zaralynda The flu vaccine doesn't necessarily cover different strains every year. – Fomite Apr 15 '15 at 15:59

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