In the 1970s, when there was still a concrete correlation between one’s academic average and admission to graduate school, a student like me had to proceed carefully. Many a grade point average had taken a torpedo amidships, launched from courses with the innocent titles such as “An Introduction to Atmospheric Science” or “The Geology of National Parks.” The law school-bound undergraduate therefore enrolled in the occasional easy-to-pass “gut” course that could help buoy the GPA while he or she struggled through philosophy or European history.

One popular option was “An Introduction to Natural Selection,” taught by the estimable Stephen Jay Gould, who was fabulous and could delight and charm us for hours. Gould didn’t have a grading curve so much as an assumption that no one would be in the least disadvantaged for wandering close to a course on natural selection.

But of all the magnificent guts, “The Sociology of Cancer” was by far the most alluring. No final exam, of course. Its overlords could be satisfied with a paper of a few thousand words, so long as it related to cancer. It would be wrong to think this was a course for jocks, because whenever writing and words can substitute for facts and formulas, its politics geeks who are being served. “Sociology of Cancer” had my name on it.

How unexpected, then, that there in that vast beer gut of a course I learned a crucial thing: Stupid, selfish people do horrible things to desperate or despairing people, for reasons varied, mysterious and beside the point.

I thought of that gut course last week when my wife and I got our vaccine booster shots.

Because during my “Sociology of Cancer” semester (Spring 1978), the newspapers were full of the story of Chad Green. He was a child suffering from a specific kind of leukemia. He was being treated by John Truman, a pediatric hematologist-oncologist who was at the time at Massachusetts General Hospital. Chad’s parents were skeptical of Truman’s cutting-edge oncology and had instead come to believe in the curative power of Laetrile, a chemical compound found in apricot pits.

As part of my coursework, I called Truman up and asked if I might visit him at the hospital, interviewing him as the matter unfolded in the newspapers, and write my essay on the case. He agreed, which of course would never happen today, if just for privacy reasons.

So I dove into the case, read everything and trooped to the hospital a few times to talk with Truman and others connected to the matter. Truman at one point sued Chad’s parents to have the boy treated, but in January 1979, the Greens fled with Chad to Tijuana, Mexico, where Laetrile was considered a legal therapy for cancer. Months later, Chad died.

The effective treatment for what Chad had was, and probably still is, hard on young patients and those who love them. Chad’s parents earnestly believed in a different course. No one, certainly not Truman, believed anything other than that they deeply loved Chad.

The experience helped me observe and internalize the capacity of some humans to willfully sell other humans on an unproven course of medical care, and its occasionally mortal consequences. Medicine can treat childhood leukemias. But someone got their hooks into the Greens and pulled them away from modern medicine.

The vulnerability of desperate, despairing or fearful people is immense. As their fear peaks, their defenses against predators weaken. The merciless swoop in. They sell the vulnerable hope — about Laetrile — or fear of vaccines and boosters.

Politics, journalism and the medical field can protect the vulnerable against merciless predators. In this pandemic, our fail-safe systems have failed. But modern medicine is even more astonishing today than in Chad’s too brief time on Earth.

On the day my wife and I zipped over to a nearby drugstore to get our vaccine boosters, I urged others on social media to do the same. The response was immediate: Some thought it catastrophic and others unpatriotic or worse. Some are certain we are being poisoned. Others that we are part of a plot of some sort.

The people who hate the booster, or even more improbably, are angry at a stranger they do not know for getting the booster, are to me the new version of the parents of Chad, who love their families but are insufficiently wary of frauds, con men and all sorts of scoundrels who are peddling the anti-vaccine message. They are also far too susceptible to would-be celebrities so eager for fame that they’d risk illness and the death of others to get it.

Some of these predators may just be cruel, but they are just as likely to be those folks I first encountered during Gould’s course, some of the many different collections of selfish genes seeking an advantage, any advantage, in a remorseless competition to survive. The anti-vaccine peddlers have convinced themselves that there is advantage in persuading others not to get vaccinated. They sense an advantage in persuading those eligible for boosters not to get boosters.

They are relentless. They are also merciless. They are also complicit.