Given that it's fall I'll necro this a little. I tend to get vaccinated for quite a bit, working at a hospital, but the flu vaccine has such poor evidence behind it that I look at it, specifically, askance. And yet flu and its variants pose such a serious threat that we can't not understand how to defeat it. I'll start by linking the most accurate evidence based research on the influenza vaccine from Cochrane (they've been restudying this very same thing since 1999): Vaccines to prevent influenza in healthy adults So, not the 10% effectiveness the news outlets are/were spouting. I tend to trust Cochrane a bit more because they've been around a while, work on donations, are excellent statisticians, and aren't affiliated with any government that I'm aware of. And yet we hear, year after year and usually from the government or pseudo-governmental agencies here in the states, that the flu vaccine is 'the best treatment we have'. I dissent. Like yon monkies above I would agree that the best way to fight the flu is via adaptive immunity. It only comes seasonally, of that there is no disagreement. What do we have lacking in the winter that we have in abundance in the summer? Cannell argues that the problem is the lack of sunlight, and the subsequent drop in vitamin D production in humans when the earth tilts: Epidemic influenza and vitamin D On the epidemiology of influenza (the tl;dr version: epidemic influenza is a symptom of epdemic vitamin D deficiency in the general population during the wintertime) Although I'm mainly in agreement with him, it's still possible that more than one 'seasonal stimulus' causes epidemic influenza. They can prove that some rodents, like ferrets, are carriers year after year. Perhaps it's not only vitamin d from sunlight, but also vitamin a from the leafy greens we get all summer and vitamin c from the various fruits and plants that are growing, that are absent during the winter. I lean toward making the flu impossible to catch. If one or both of the above suppositions are correct, you can make it impossible to catch the flu simply by simulating a summertime environment during the winter: 1. Get a UV light for tanning your hands during the winter (or take oral vitamin D3; the only case of an overdose that I could find was a gentleman that was prescribed 50,000 iu/day mistakenly for 3 months. His symptoms resolved by stopping the vitamins for a bit ). You'll see the RDA of 2000 iu/day. This is ok if you're getting 30 mins of (not winter) sunlight and not taking anticonvulsants. In the summer your body will produce around 20,000 iu of D3 in about a half an hour, and promptly stop producing after that. In the winter, it's only got what vitamin d that you got from fish, or supplements, or mushrooms. Or what's stored in your fat. In any case, in wintertime, the RDA for vitamin D is woefully inadequate. 2. Vitamin C. Anything more than the RDA you'll just poop out. 3. Vitamin A, or fresh leafy greens containing an abundance thereof. I ignore the wintertime temperature because if temperature is a factor, then I don't have an answer .