Flu, Light, And Truth: FLUx et Veritas

Flu, Light, And Truth: FLUx et Veritas
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I am getting a flu shot, and so are all members of my family ― and you should, too. That’s the simple truth in plain light, and unlike this dangerous infection, it involves no flux from year to year. That was my position last year at this time, and it will be my position next year.

Hence my title, a play on the words gracing the Yale University coat of arms I have walked by countless times over the past 25 years: Lux et Veritas (light and truth). This is just the right time for an annual booster of light and truth regarding the perennial menace of the flu, and our best defenses against it.

That we need such a booster at all is testimony to several things. First, the truth about flu recedes readily into the shadows of denial, conspiracy theories, and anti-scientific New Age nonsense. A bit of light is just the right disinfectant.

Second, the influenza virus is wily enough to require a reintroduction every year at this time. That’s because the virus changes its protein coat annually, so last year’s strain is yesterday’s news. CDC epidemiologists do all they can to tell us what’s coming each fall. Well, it’s fall ― and this year’s verdict is in.

Let’s start with a general primer. The “flu” refers to an upper respiratory infection caused by a small group of closely related viruses. The virulence, or strength of the flu strain varies every year. The illness caused by the virus is never pleasant, but when the strain is very virulent, the illness can be severe. Although the flu, per se, generally does not cause death in otherwise healthy people, more than 30,000 premature deaths each year in the U.S. alone are attributed to influenza, mostly in older adults, the very young, or those prone to complications due to prior illness or a history of smoking.

When the flu strain is especially severe, being the right age or having generally good health make for less reliable defense. 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.

Part of the toll of the 1918 pandemic was attributable to the strain of the flu, and part to the turmoil of World War I. But there was, of course, no vaccine in 1918 as there is now, and that may also partly explain why we have seen no commensurate outbreak since. Vaccination, however, is only protective when we roll up our sleeves, and too few of us do.

Most vaccines provide protection over an extended period of time. The flu vaccine is unique because the influenza germ itself is unique. It undergoes a process known as “antigenic drift” that changes the germ’s surface proteins every year (that’s the “flux”), so that this year’s flu is generally uncovered by last year’s vaccine. The CDC and the WHO track the emergence of flu strains in Asia each year, and develop a vaccine based on the particular surface proteins that predominate. The virus is also subject to more abrupt changes, known as “antigenic shift,” which occur when flu strains mingle with one another, usually in domestic animals, notably pigs and ducks. That is the process that produces pandemic strains of flu with reference to the source: avian, or swine.

Immunization works by priming our immune system to attack the virus by stimulating it with those surface proteins, known as antigens because they “generate” the formation of “antibodies.” The flu antigens in the vaccine look like the flu virus to our immune system. After the vaccine, if we are exposed to the flu, our immune system recognizes the germ as a foreign invader against which it has laid down preparations, and launches a quick and effective attack. When all goes as hoped, the virus is eradicated before we get sick.

In general, it takes our immune system several weeks after exposure to antigens to develop a robust supply of antibodies. Consequently, the best time for flu vaccine is before the bug is established among us. Based on continuous CDC surveillance, that’s now.

We have recent evidence of what has been an obvious, advancing, and to those of us in public health, alarming trend over recent years: vaccine complacency, and vaccine opposition. The latest news on that front is survey research indicating that a high number of millennials don’t plan to immunize their children. Perhaps this is the same group planning to sit out the presidential election, too, and count on nihilism at the sidelines to work out well. Good luck with that.

In case you are among the many dubious about flu vaccination specifically, and immunization in general, I will address it bluntly. By and large, doubts and conspiracy theories about vaccines are the privilege of the very societies that are the greatest beneficiaries of them. Stated differently, populations succumbing to polio and smallpox don’t tend to fret the theoretical harms of vaccination. We needn’t go so far; high rates of measles, mumps, and rubella tend to make vaccine enthusiasts of parents as well.

The flu vaccine does not cause the flu ― ever. It can’t because the vaccine does not contain a virus, just proteins. There is no infectious agent in the vaccine; viral proteins cannot replicate or cause disease (N.B. the nasal flu vaccine does contain live virus, but is not recommended this year). Everyone knows someone who swears they got the flu after the flu shot. The problem is, we often refer to any severe upper respiratory illness as “the flu” (while referring to less severe cases as “a cold”), and viral upper respiratory infections are common in the fall and winter when the flu shot is given. If you get a viral infection shortly after getting the flu shot, you may assume it is due to the vaccine, even though it is not. The immune system response to the vaccine can at times make people feel slightly ill for several days, but that’s a far cry from a true bout of flu, which tends to last more than a week and cause, among other things, severe muscle pain and high fever.

Doubts also seem to abound 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. There have been also been recent improvements to the vaccine to enhance immune responses in those who most need such help.

But there’s another key consideration here, courtesy not of epidemiologists, but the poet and preacher, John Donne: no one is an island. Your vaccine may save someone else’s life. 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. This is called “herd immunity,” and it is an important reason why smallpox and polio no longer threaten us all.

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 each year, 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. As noted, I readily accept that risk every year not only for myself, but for my beloved wife and children as well (or at least I did all the years they lived at home). I put the arms of the people I love most on the planet where my mouth is on this topic.

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- is amplified many orders of magnitude by repetition in the blogosphere. One case, appearing on 50,000 websites, exerts the influence of 50,000 cases. The same is true even when the allegations are entirely false, like the non-existent link between immunization and autism.

But at least as important, we are generally blasé about risks that lack the intrigue of conspiracy. So, for instance, consider if flu infects one person in 5, 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 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.

In contrast, the most dangerous flu vaccine in history ― the notorious swine flu debacle of 1976, when there were adulterated vaccines in the mix ― was associated with 25 deaths. That’s bad ― but it is more than two orders of magnitude less bad than even the mildest of flu seasons.

Another argument I hear against vaccination is like that proverbial “Uncle Joe” everyone knows, who smoked 3 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.

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 small pox or polio immunization never had small pox or polio, either. If they ever had, it would have been too late for those vaccines to do them any good.

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.

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 gall bladder or occluded arteries. Convinced as I am of the benefits of immunization, I feel a momentary hesitation each year myself. But I get over it, and roll up my sleeve. I recommend you do the same.

If I’ve failed to convince you, or you get the vaccine too late to prevent influenza, there is medication available to shorten the course of illness and reduce the risk of complications. If you develop fever, headache, cough and/or body aches, contact your doctor to find out if you are a candidate. The CDC provides very helpful information about antiviral medications on-line.

The simple truth is that the flu ranks among the great infectious disease killers in human history, and is an unusually wily germ into the bargain. Even a garden-variety bout is apt to lay you out for a week or more. There is flux in the composition of the virus year to year, but none in the public health recommendation based on science, sense, and the dispassionate light of epidemiology: you should defend yourself and your loved ones from this perennial threat.


Director, Yale University Prevention Research Center; Griffin Hospital

Senior Medical Advisor, Verywell.com

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