This story originally appeared in Kids Today, Voxs newsletter about kids, for everyone. Sign up here for future editions.In the 19th century, it was incredibly dangerous to be a child.As of 1900, about 18 percent, or nearly one in five, American children died before their fifth birthday. The most common causes were infectious diseases pneumonia, diphtheria, dysentery, measles, and other illnesses ran rampant through households, and children were especially at risk.Cities, in particular, were cauldrons of infection, Samuel Preston, a demographer and co-author of the book Fatal Years: Child Mortality in Late Nineteenth-Century America, told me. But around the country, communicable diseases were rites of passage of childhood, some of them far worse than others, but all of them causing serious morbidity, and a lot of them causing death, said Howard Markel, a historian of medicine who has studied epidemics.Today, by contrast, less than 1 percent of children die before the age of 5, and until recently, once-common childhood diseases like measles were essentially unheard of in the US. What changed?Better sanitation and understanding of germ theory are part of the story, but one key factor thats transformed American childhood over the past century is the widespread adoption of vaccines. Today, children in the US are routinely vaccinated against measles, mumps, rubella, diphtheria, polio, some types of pneumonia and meningitis, and more. Other vaccines, including for typhoid, are in use around the world.This public health victory has saved hundreds of millions of lives and prevented billions of cases of disease. On a list of the 10 greatest hits of medicine, Markel said, at least nine would be vaccines.That message has been getting lost lately, thanks to a rise in anti-vaccine sentiment around the US and the world, exemplified most recently by the confirmation of Robert F. Kennedy Jr. one of the countrys most prominent vaccine skeptics, as the secretary of Health and Human Services. Just weeks into Kennedys tenure, a measles outbreak has sickened more than 100 people and killed an unvaccinated child in Texas, the first death from measles in the US in nearly a decade.In this time of falling vaccination rates and rising risks of preventable disease, I wanted to flash back to the long period of human history before vaccines were available. Childhood in the centuries before vaccination was marked by illness, yes, but also by grief and loss in a way that we tend to forget now that disease outbreaks are more of a rarity. Understanding that can teach us about the consequences, for families and society, of the choices we make today.When sickness and death were the normIn the years before vaccines, the prevalence of illness meant untimely death touched nearly every family. Most parents as late as 1900 could expect to lose at least one child to disease, Steven Mintz, a history professor at UT Austin who has studied childhood, told me in an email. That meant most children could expect to lose at least one sibling sometimes more, given the large families of the time.James Marten, a historian who has studied childhood, recalls a gravestone with three names on it in his familys local cemetery: They were my grandfathers sisters and brothers that all died within a week or two of each other, he told me.Theres a misconception that larger family size and the near-inevitability of childhood disease made the loss of a child less devastating for those who survived. In fact, parents suffered extraordinary grief when children died, Mintz said.After the death of her son Willie from typhoid fever in 1862, for example, Mary Todd Lincoln wrote in a letter, My question to myself is, can life be endured?Nor were children spared this grief. They might join in mourning a late-19th century photograph of heir Helen Frick as a young girl shows her wearing a locket containing a picture of her dead sister. They might also encounter constant reminders of their loss in the form of a new brother or sister with the deceased siblings name a common practice in a time of high infant mortality.Though sickness struck people from all walks of life, poor children and children of color faced additional risks. New sanitation infrastructure like sewers, that limited the spread of disease, were installed in wealthy, white neighborhoods first, leaving poorer families vulnerable, said Nancy Tomes, a history professor at Stony Brook University who has studied the history of disease. Hundreds of thousands of Native American children, meanwhile, were sent to boarding schools, often by force, where poor sanitation led to frequent disease outbreaks and a staggering number of deaths.Death and serious illness are staples of literature for and about children in the 19th century, often inspired by real-life loss. The illness and death of Beth, from complications of scarlet fever contracted from a baby, in Louisa May Alcotts Little Women mirror Alcotts own sisters death in 1858, writes pediatrician Perri Klass. Laura Ingalls Wilders older sister Mary went blind in 1879 (when Laura was 12 and Mary was 14), likely from meningoencephalitis, an episode that shows up in Wilders book By the Shores of Silver Lake: the fever had settled in Marys eyes, and Mary was blind.While many infectious diseases disproportionately affected children, adults died too, and in the 19th century, as many as half of all children could expect to lose a parent by the age of 21, Mintz said. The psychological toll was enormous. There was also an economic and practical toll. Widowed mothers and their children, unable to support themselves, often had to enter almshouses or poorhouses in the 19th century, Tomes said. If a mother died, the father might send the children to live with relatives, or to an orphanage, which were packed in this time, Tomes said.For those who got sick, meanwhile, the experience of disease itself could be painful and terrifying. Diphtheria, for example, causes a thick membrane to form at the back of the throat, making it very difficult to breathe. The disease was called the strangling angel, Mintz said. If children made it through the first phase, they might die six weeks later of heart failure, Markel said.Even the survivors of infectious diseases could face lifelong effects. Polio, for example, could lead to paralysis, and some children spent weeks, months, or even years encased in an iron lung to help them breathe. (One of the last users of an iron lung, Paul Alexander, died last year after over 70 years with the device.) Devastating though they could be, endemic diseases like measles became expected in the years before widespread vaccination: it was a fact of childhood life that you were going to get sick with one of these, Markel said.Polio, which arrived in the US in the late 19th century and led to more isolated, unpredictable outbreaks, caused more fear, Markel said. Parents kept children out of school, swimming pools, and movie theaters. It very much shapes your daily life and what you do entirely once people learn about these things, Merle Eisenberg, a history professor at Oklahoma State University who studies pandemics, told me.The polio vaccine, introduced in 1955, put an end to those fears. Today, its one of a series of vaccinations that, together, allow most children in wealthy countries to grow up free from the infectious diseases that sickened and killed so many of their forebears. We take it for granted the opportunities and the possibilities that children now have, Eisenberg said.These diseases arent gone, however. In higher-poverty countries where vaccine distribution is more of a challenge, preventable diseases still claim childrens lives, Rashida Ferrand, an epidemiologist at the London School of Hygiene and Tropic Medicine, told me. Cases of diphtheria are on the rise in Pakistan, and polio remains endemic there and in Afghanistan.As the Texas measles outbreak shows, the diseases that devastated families for centuries can come back here too. And remembering the history of childhood before vaccines is especially critical now, experts say a time when vaccination is being widely questioned, and the rampant disease and grief of the last several millennia of human history have faded from public memory (Covid pandemic notwithstanding).Its a past that we have largely forgotten, and it is so wretched a prospect, we should have it in mind as a possibility if we go down this road, Preston said.What Im readingThis years flu season has been especially devastating for children, but doctors say vaccination can help protect kids from severe illness.The New York Times asked eight kids what they took with them when they evacuated from the Los Angeles wildfires; results include a sword and a turtle named Turtleicious.Peppa Pig, the popular TV character who has taught a generation of American toddlers to speak in British English, is getting a new baby sibling.This week my little kid and I are enjoying Fifteen Animals!, a Sandra Boynton classic with a SHOCKING TWIST.From my inboxIn response to my story last week on trad kids, a reader wrote in about growing up as the second-oldest of five children in a religious home, forced to essentially school myself from the age of probably 13 using books or computer programs. Im sure I was expected to become a stay at home mother and no one was worried about my lack of career path, the reader wrote. I was depressed and terribly introverted and antisocial, and despite everything I ended up transitioning to male-nonbinary, Im queer and self-supporting, Im pursuing an education and planning on studying abroad in a country Ive always wanted to live in.Thanks so much to this reader for sharing your experience, and as always, you can get in touch with questions or suggestions for future stories at anna.north@vox.com.See More: