By DAVID KATZ, MD

The CDC has noted an early and nasty start to the flu season. Perhaps their own website has caught it, because as I’m writing this, the whole thing is down. Assuming it recovers, I will insert relevant links per routine. Otherwise, I wish it well, and leave you to find your way there on your own.

It’s a bit soon to say, but the virus and the outbreak pattern at this point seem to resemble those of the 2003-2004 flu season, in which nearly 50,000 Americans died. At least two children have already died of flu complications this fall.

This is not the sort of stuff a public health physician can ignore.

So, I recently noted on LinkedIn andTwitter that I’ve been vaccinated — as I am every year — and recommend this year’s vaccine, which appears to match the prevailing viral strain quite well, to everyone else. I promptly got comments back from naysayers, including at least one self-identified microbiologist, who noted he never got vaccinated, and had “never gotten the flu.”

I believe him. But this is like that proverbial “Uncle Joe” everyone knows, who smoked three packs a day and lived to be 119. It could happen — but I wouldn’t bet the farm on it. Uncle Joe is that rare character who somehow comes away from a train crash with a minor flesh wound. The rest of us are mortal.

But there is something more fundamentally wrong with the “I’ve never gotten the flu, and therefore don’t need to be vaccinated” stance than the Uncle Joe fallacy. Let’s face it — those who were ultimately beneficiaries of smallpox or polio immunization never had smallpox or polio, either. If they ever had, it would have been too late for those vaccines to do them any good.

Not all that long ago in the grand scheme — when our parents were children — polio was the dreaded scourge of summer. Our grandparents knew that the advent of summer meant a reasonable chance that one of their children would be infected with the polio virus, and possibly come away crippled for life as a result. Immunization put an end to this, of course. But all of the beneficiaries of it — all those children who never were crippled by the virus — could say just what the nihilistic microbiologist said. They never got polio.

The same is true of smallpox, one of the most dreaded killers in human history, and still the only infectious disease willfully eradicated. We can no longer say how many millions of lives have been saved by the smallpox vaccine. (Which was, by the way, the original “vaccine,” and the reason for the name. The word “vaccine” comes from the Latin word for cow, and refers to the fact that the smallpox vaccine was derived from cowpox.) But we can say that no one saved by the vaccine ever had smallpox before they got it.

The trouble with serious illness is that one time can be one time too many.

Familiarity breeds contempt, or at least complacency, and perhaps the annual return of influenza has induced that response. Perhaps that’s why we seem to be dismissive of this germ, and overlook what a serious illness it can be.

But that tendency is at our peril. The single greatest infectious disease calamity in all of human history was not plague, or typhus, or smallpox — it was the 1918 flu pandemic, which killed as many as 50 million. Those who don’t respect the flu just aren’t paying attention.

That said, I do understand the reasons for reticence about immunization in general, and flu immunization in particular.

For any vaccine to do us any good, we need to get it while feeling fine. This is quite different from, say, an operation that is much more dangerous — but easily justified by the obviously hemorrhaging bullet hole, plugged-up gallbladder or occluded arteries. Convinced as I am of the benefits of immunization, I feel a momentary hesitation each year myself.

It can be hard to talk ourselves into rolling up our sleeves and getting jabbed with a needle when healthy, even if we are not particularly worried about a government conspiracy. With a little nudge from conspiracy theories — up to and including allegations of flu vaccine used for purposes of willful genocide — however unreliable the source, doubt can become insurmountable.

There are several reasons why the potential harms of flu vaccine may loom much larger in the imagination than they actually are. First, any adverse event — an allergic reaction, the now exceedingly rare case of Guillain-Barré syndrome, or anything else — is amplified many orders of magnitude by repetition in the blogosphere. One case, appearing on 500,000 websites, exerts the influence of 500,000 cases.

There is also our prevailing tendency for risk distortion. Consider if flu infects one person in five, and kills one person per 10,000 infected. There is certainly a good chance you, if healthy, would not be among those who get the flu. There is a very good chance the majority of people you know would not get the flu, either. And you are very unlikely to know anyone who is killed by the flu.

But one infection per five means 60 million or so infections nationally. One death per 10,000 of these infections might be invisible in your circle of friends and family, but it would mean 6,000 deaths nationwide. This is consistent with a quite mild flu season in the U.S. A bad season is 10 times worse — to say nothing of a truly dreadful season.

In contrast, the most dangerous flu vaccine in history — the notorious swine flu debacle in 1976 — was associated with 25 deaths. That’s bad, of course, but it is more than two orders of magnitude less bad than even the mildest flu season.

Perhaps a more legitimate roadblock is doubt about the effectiveness of the flu vaccine. It is certainly far from perfect, and the elderly — who most need protection — may need two inoculations to get it. But leaving aside some of the subtleties that complicate measuring vaccine effectiveness in real-world settings, and applying even a low-level estimate of overall vaccine effectiveness, routine flu vaccination produces a decisive overall benefit compared to just taking our chances with the flu.

We should also recognize that when it comes to contagion, not one of us is an island. While true that the elderly most need protection and benefit least from vaccination, there is another way to protect our older loved ones: Vaccinate ourselves and our children. People who can’t get the flu can’t transmit the flu to those most vulnerable to it and its complications.

I have recently read The Wild Life of Our Bodies, and am currently reading An Epidemic of Absence, and these books raise an issue that warrants brief mention here. We can overshoot in our zeal to banish potential infectious agents, and the result may be other ills — from allergies, to asthma, to serious autoimmune diseases. We clearly don’t want these, any more than we want river blindness. The right balance is a work in progress, a fascinating area of inquiry and research — and a topic I will certainly revisit in future columns. For now, we may simply note that there is nothing in the work thus far to suggest that bouts of influenza do us any good.

Unlike that microbiologist, I have had influenza — several times over my 50 years. All but one bout were in the years before I got the vaccine annually. One case, the most recent, was despite the vaccine, and obviously a strain from which I was unprotected. I’m quite healthy, and recovered each time — but it was a truly miserable experience. There were moments when I really wanted to die!

Whatever your doubts about the influenza vaccine, it is an established fact that immunization is many times — many times — safer than the flu itself. That does not mean flu is a plague, nor that the vaccine is perfectly safe. Nothing in medicine and little in life is perfectly safe. Harm from the flu vaccine is possible, but a highly remote risk. For what it may be worth to make this personal, I readily accept that risk every year not only for myself, but for my beloved wife and children as well. I put the arms of the people I love most on the planet where my mouth is on this topic.

So, I am unimpressed and unpersuaded by those who argue against flu vaccination because they have avoided the flu without it.

You presumably know the expression — unless, that is, you are George W. Bush — “Fool me once, shame on you, fool me twice — shame on me.” If you are George W. Bush: Thank you, Mr. President, for reading my column — no offense — hope those English lessons are coming along, and please get a flu shot.

For everyone else, the relevant point is this: Influenza unashamedly kills tens of thousands of us ever year. Being fooled by it even once could be one time too many.

David Katz, MD, MPH, FACPM, FACP, is the founding (1998) director of Yale University’s Prevention Research Center. This piece first appeared at The Huffington Post.