The other day I asked a longtime patient of mine, a woman in her 90s, whether she'd like a flu shot. "Absolutely not!" she snapped. You'd have thought I'd proposed major surgery. Actually, I have proposed major surgery to this woman, and she's accepted it readily. But a flu shot? "Absolutely not!"

Another patient told me that she didn't want a flu shot because she didn't believe in putting live germs in her body. I informed her that, in fact, the injectable influenza vaccine contains no live virus. This did not sway her.

Then there was the man who didn't see why he should have a vaccine to prevent a disease he'd never contracted. I pointed out that he was taking medication for high blood pressure and high cholesterol to prevent heart attack and stroke — also conditions he'd never had. He remained unconvinced.

As I do every year at this time, I'm seeing many patients who refuse the influenza vaccine. This refusal used to frustrate me. OK, it still frustrates me. But I think I understand it better than I used to. I've come to realize that deciding not to have a flu shot may have less to do with opposition to the vaccines themselves than with my patients' desire to regain a measure of control in a health care system that often makes them feel powerless.

Certainly, there are some who believe, mistakenly, that flu shots cause the flu or colds or other illnesses. It takes the rap for all runny noses, coughs, and fevers because the vaccine isn't 100 percent effective (last year's flu shot was a relative dud, though this year's is projected to work better), takes two weeks to kick in, and is given during cold and flu season. But that's like blaming umbrellas for the rain.

People old enough to remember the swine flu scare of 1976 may have bad associations with influenza vaccines, and even people who weren't yet born then may have absorbed a vague sense that flu shots are unsafe. (I see a similar wariness about IUDs among women who have heard about the Dalkon Shield, a dangerous version of the contraceptive device that's been off the market for 40 years).

In On Immunity: An Inoculation, an elegant 2014 book about vaccine phobia, Eula Biss points out that as far back as the 18th century, when an early version of the smallpox vaccine was developed, people distrusted the idea of having foreign substances injected into their bodies. She notes that the fact that vaccination is practiced as much for the health of the public as the individual may make it that much harder to accept. The rhetoric of the modern anti-vaccine movement often pits personal liberty against the common good. Indeed, a few of my patients do see the flu vaccine as an intrusion, imposed on them by Big Pharma, the government, and, more and more frequently, their employers. This view finds plenty of validation on the internet, where people are encouraged to empower and inform themselves (often with dubious medical information) rather than submitting passively to doctors' orders.

More often than not, though, patients can't tell me why they don't want a flu shots, they just don't. I sense that they've made, even if subconsciously, a risk-benefit calculation; for a perceived low risk they get, in return, absolute control over their health care, if only in the small domain of the flu shot. They'll take their chances on getting the flu because they think it will be like a cold, only a bit worse. They'll sip ginger ale, binge watch "House of Cards" and wait it out. (The truth is, an actual case of influenza can leave you aching from head to toe, fevered and shivering, and clinging to your damp, roiling mattress for days like a shipwreck survivor. Respiratory distress, dehydration, bacterial superinfection, or other complications of flu send about 200,000 Americans to the hospital and kill thousands every year.)

I first formulated this theory not in my clinic, but, rather, in the hospital cafeteria.

A few years ago, an older woman who worked the midday shift was unflappable as diners — most of them patients and their families — barked their instructions: Not that piece of fish, the other one! Too much mustard!

One day, as she was making my sandwich, I asked her how she kept her cool. "The way I figure it," she told me, "around here people don't feel they can control much. Can I blame them for wanting to control lunch?"

I've been channeling that wise woman these fall days. Patients may not be able to do much about lousy insurance, pricey medications, or ever-shorter visits with ever-more-distracted doctors — not to mention the human body's unfortunate tendency to age, sicken, and die. But they can say no to flu shots. I don't agree with them — but can I blame them?

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