PUBLISHED August 16, 2019

Like most American children of my generation, I lined up with my classmates in the mid-1950s to get the first vaccine for polio, then causing 15,000 cases of paralysis and 1,900 deaths a year in the United States, mostly in children. Likewise, we lined up for the vaccine against smallpox, then still causing millions of deaths worldwide each year. I’ve continued to update my immunizations ever since, including a few exotic ones for National Geographic assignments abroad, among them vaccines for anthrax, rabies, Japanese encephalitis, typhoid, and yellow fever.

Having grown up in the shadow of polio (my uncle was on crutches for life), and having made first-hand acquaintance with measles (I was part of the pre-vaccine peak year of 1958, along with 763,093 other young Americans), I’ve happily rolled up my sleeve for any vaccine recommended by my doctor and the U.S. Centers for Disease Control and Prevention, with extra input for foreign travel from the CDC Yellow Book. I am deeply grateful to vaccines for keeping me alive and well, and also for helping me return from field trips as healthy as when I set out.

One result of this willingness, however, is that I suffer, like most people, from a notorious Catch-22: Vaccines save us from diseases, then cause us to forget the diseases from which they save us. Once the threat appears to be gone from our lives, we become lax. Or worse, we make up other things to worry about. Thus, some well-meaning parents avoid vaccinating their children out of misplaced fear that the MMR vaccine (for measles, mumps, and rubella) causes autism. Never mind that independent scientific studies have repeatedly demonstrated that no such link exists, most recently in a study of 657,000 childrenin Denmark. (Discover the strange history of vaccines.)

This irrational fear is why the United States has experienced almost 1,200 cases of measles so far this year, almost two decades after public health officials proudly declared it eliminated. About 124 of the victims, mostly children, have been hospitalized, 64 of them with complications including pneumonia and encephalitis, which can cause brain damage or death.

And yet autism can still seem like a bigger threat than measles, if only because it appears in countless television shows and movies such as Rain Man and Gilbert Grape. Meanwhile, you’re more likely to catch measles at a movie theater than see the disease featured onscreen.

close Seeking out the unvaccinated in Karachi, Pakistan, a health worker finds a boy who lacks the mark on his finger that would indicate he’s previously been inoculated against polio. The oral vaccine has to be dispensed quickly, before the train pulls out. Photograph by William Daniels, Nat Geo Image Collection close Fighting a measles outbreak in the Democratic Republic of the Congo, workers with Doctors Without Borders shuttle coolers full of vaccine across a river. On their arduous 10-hour circuit of affected villages, they must keep the vaccine perfectly chilled. Photograph by William Daniels, Nat Geo Image Collection close Just vaccinated against yellow fever, a young Congolese woman waits for her disinfected arm to dry. Serious attacks of the virus are vicious, causing internal hemorrhage, vomiting, liver damage, and death. Photograph by William Daniels, Nat Geo Image Collection close With a yellow fever outbreak spreading from neighboring Angola and vaccine in short supply, health workers in the DRC struggled to inoculate all 350,000 residents of the city of Matadi. Here they improvise a clinic in an abandoned truck. Photograph by William Daniels, Nat Geo Image Collection close A Congolese mother brings her children to be vaccinated at a church in the village of Nzerret. Photograph by William Daniels, Nat Geo Image Collection close Tap images for captions

And so, parents forget, or more likely never knew, that 33 of every 100,000 people who experienced actual measles ended up with mental retardation or central nervous system damage. (That’s in addition to those who died.)

They forget that an outbreak of rubella in the early 1960s resulted in 20,000 children being born with brain damage, including autism, and other congenital abnormalities.

They forget that, before it was eradicated by a vaccine in the 1970s, smallpox left many survivors blind, maimed, or brain damaged. (Read how the vaccine for smallpox was invented.)

One remedy for this Catch-22 is to make a conscious effort to remind ourselves about the world before vaccines. Tdap, for instance, is a recurring but somewhat puzzling item on my immunization card. (Children get a slightly different formulation called DTaP.) The "T" is for tetanus and the "P" for pertussis, or whooping cough. But I was totally ignorant about the "D" for diphtheria.

A school doctor and a county health nurse vaccinate a young man against smallpox in Gasport, New York, in March 1938. Photograph by Harry Chamberlain, FPG/Hulton Archive/Getty

Even doctors now tend to know the disease only from textbooks. But before the development of an effective vaccine in the early 1940s, diphtheria was among the great terrors of childhood. It killed more than 3,000 young Americans one year in the mid-1930s, when my parents were in high school. It is once again killing children today in Venezuela, Yemen, and other areas where social and political upheaval have disrupted the delivery of vaccine.

Among other symptoms, diphtheria produces a gray membrane of dead cells in the throat that can block a child’s windpipe, causing death by suffocation. Hence one of its nicknames: “the Strangling Angel.”

New England, where I live, suffered one of the deadliest epidemics in the 1730s and ‘40s—“the most horrible epidemic of a children’s disease in American history,” according to one historian. It was made more horrible by the commonplace idea that it had been sent by God to punish sinful behavior. Or as a 1738 verse warned misbehaving boys and girls:

So soon as Death, hath stopt your Breath,

Your souls must then appear

Before the Judge of quick and dead,

The Sentence there to hear. //

From thence away, without delay,

You must be Doom’d unto,

A dreadful Hell, where Devils dwell,

In Everlasting woe

Diphtheria was terrifying not only because it could kill with stunning speed, but also because it could hopscotch so easily from child to child by way of the coughing and sneezing it induced. Some families may also have unwittingly hastened the dying by having children line up to kiss a dying brother or sister goodbye. The results are still evident in our local burial grounds.

In Lancaster, Massachusetts, for instance, mottled slate tombstones lean together, like family, over the graves of six children of Joseph and Rebeckah Mores. Ephraim, age seven, died first on June 15, 1740, followed by Hannah, three, on June 17, and Jacob, eleven, a day later. All three were buried in one grave. Then Cathorign, two, died on June 23, and Rebeckah, six, on June 26. The dying—five children gone in just 11 days—paused long enough to leave the poor parents some thin thread of hope. But two months later, on August 22, Lucy, 14, also died. A few years after that, diphtheria or some other epidemic disease came back to collect the three remaining Mores children.

Karachi shopkeeper Ghulam Ishaq didn’t trust the polio vaccine. Now he blames himself for the double misery of his four-year-old daughter, Rafia: one leg withered by polio, the other broken by a car she couldn’t dodge. Photograph by William Daniels, Nat Geo Image Collection

Joseph and Rebeckah were by no means alone in their tragedy. Many other parents also lost all their children to diphtheria, in one case 12 or 13 in a single family. (In their stunned grief, the parents could not put an exact number on their loss.) On a single street less than a half-mile long in Newburyport, Massachusetts, 81 children died over three months in 1735. Haverhill, Massachusetts, lost half its children, with 23 families left childless.

Parents now rarely know such grief because our children are protected by vaccines, including Tdap/DTaP. It’s why we feel secure in having smaller families. It’s also a major reason life expectancy at birth in the United States increased from 47.3 years at the start of the twentieth century to 76.8 at the end.

The level of this protection has continued to increase year by year in our own lifetimes, though the terminology of recommended immunizations tends to obscure these improvements. No parent has ever lost sleep, for instance, about something called “Hib,” short for “Haemophilus Influenzae Type B,” or about another pathogen called “rotavirus.”

But when he was starting out in the 1970s, “Hib dominated my residency,” says vaccinologist Paul Offit, M.D. It’s a major cause of childhood meningitis, pneumonia, and sepsis, a systemic blood infection. Children with this bacterial infection came into the emergency room so routinely that the hospital maintained a special darkened room with a fish tank to calm the child while an anesthesiologist rushed down and a surgical team prepared to operate. The danger, if the child became excited, was that the swollen, inflamed epiglottis would begin to spasm, blocking the windpipe.

“I had a lot of really painful conversations with parents when kids had meningitis or sepsis,” Offit recalls. “Often kids would have permanent hearing loss, intellectual deficits, motor deficits.”

Stanley Plotkin, M.D., also a vaccinologist, started out in the 1950s. Sixty years later he still recalls helplessly watching a child with a Hib disease “die under my hands.” A tracheostomy—a tube inserted through an incision in the windpipe below the blockage—would sometimes help. “But at the time I was an intern and didn’t know how to do a tracheostomy.”

Lab technicians examine samples of a pathogen called rotavirus, the leading cause of children’s diarrhea, which sickens millions every year. In the poorest countries of sub-Saharan Africa and South Asia, it kills by the hundreds of thousands. Photograph by William Daniels, Nat Geo Image Collection

Doctors (and parents) starting out today need not live with that particular memory. An effective vaccine introduced in the 1990s has reduced incidence of Hib disease in the United States by 99 percent, down from 20,000 to as low as 29 cases a year.

Rotavirus is an equally unfamiliar term for most parents. But it used to infect almost every child before the age of five and cause about 40 percent of severe infant diarrhea cases. In the absence of medical treatment, dehydration led to between 20 and 60 deaths a year in the United States and 500,000 deaths worldwide.

A vaccine for rotavirus became available in the 1990s, and in 2006 the CDC approved a safer version developed by Offit and Plotkin, together with the late H. Fred Clark, a microbiologist and social activist. Rotavirus-induced diarrhea has become rare as a result, preventing 40,000 to 50,000 hospitalizations of U.S. infants and toddlers every year. But in a California rotavirus outbreak in 2017, a child who had not been vaccinated still died of the disease, two months before its second birthday.

It is of course true that vaccinations entail risks, like everything else in the world. They range from the commonplace, like soreness at the site of injection, to the vanishingly rare, like a potentially life-threatening allergic reaction. Medical researchers are typically the first to identify and characterize these risks. A CDC study in 2016, for instance, looked at 25.2 million vaccinations over a three-year period and found 33 cases of severe vaccine-triggered allergic reaction—1.3 cases per million vaccine doses. (Here's how the measels vaccine protectss against more than just the measels.)

Kids on Vashon Island, Washington—where many parents are wary of chemicals—have long been poster children of the anti-vaccination movement. But vaccination rates are rising in response to measles outbreaks and the efforts of public health workers. Photograph by Richard Barnes, Nat Geo Image Collection

How should parents think about a risk like that? Being a good parent isn’t about protecting children from every medical risk. Instead, it’s about making a judgment, with advice from a doctor, about relative risk. Ask yourself: Which is worse for my child—the remote possibility of an allergic reaction, or the risk of Hib disease, rotavirus, pneumonia, or even chickenpox—which, despite its trivial reputation, killed 100 to 150 American children a year before the 1995 approval of an effective vaccine? Which is worse, a fictitious link between the MMR vaccine and autism—now dismissed as fraudulent even by the journal in which it was originally published—or exposing your child every day to the possibility of measles, with all its potentially deadly or debilitating consequences?

For my wife and I, the decision was always to get our children their recommended vaccinations. We still worried, as all parents do. But they stayed healthy, and we slept better, knowing we had put so many medical terrors of the past safely behind us.