Vaccination and Politics

It took the world about a decade of concerted effort to eradicate smallpox -- the last "wild" case of the disease was in Somalia in 1978 (someone died of the pox in a British lab accident a few years later). The campaign to eradicate polio began in 1988 and will certainly reach the 20-year mark without finishing. To understand why, it's helpful to read this sad Reuters post from Iraq. http://www.alertnet.org/thenews/newsdesk/IRIN/cde520844242e6fd0dc635d48580390a.htm

HPV - The Ad

Last week, late at night in my Japanese-style 8x6 New York City hotel room, I was zapping through the TV channels when I came upon a most peculiar advertisement. In it, black, white and Hispanic tweens, teens and young women were skipping rope, running in marathons, waiting for subway trains and generally looking proud to be young and female. They were also smiling happily and holding up signs that had the number "1" printed or painted on them. This, it turned out, was an ad for Merck's new Gardasil vaccine, which protects against the human papilloma virus, the microorganism that causes cervical cancer. The theme of the ad was "One Less Life Affected by Cervical Cancer."

Flu Vaccination--why bother?

Not always for the reasons you'd think

Booklist

Pulling together years of accumulated research on a topic he has written about for several national publications, Allen recounts the 200-year history of vaccination, from its first employment to combat smallpox, "the first and only contagious disease ever eradicated" by a vaccine, to the present, in which decades of unanswered questions plus low profit margins for vaccine development threaten its future. Allen undertakes a ponderous mission indeed because there has been so much controversy, most recently regarding an alleged link between autism and a vaccine, and disagreement over the efficacy of various vaccines. A 2005 study found little difference in fatality rates between elderly flu shot recipients and those who didn't get the shots, and then there's the whole discussion about how much social responsibility the individual must bear when getting a vaccination that puts the recipient at risk of unwanted side effects but also helps protect the community from an epidemic. Thorny issues all, which Allen deftly maneuvers as he wrangles myriad aspects of a very complicated issue into a comprehensible text. Donna Chavez
Copyright © American Library Association. All rights reserved

Five Triumphs of Vaccination–and Five Tragedies Along the Way

1. Smallpox

Triumph: The Eradication of Smallpox. A global campaign led by D.A. Henderson of the CDC (then the Communicable Disease Center) tracks smallpox down to its last redoubts in south Asia and Africa. The last case of wild smallpox is reported in 1975, when Ali Mao Maalin, a Somali vaccine worker, becomes ill with a mild  form of the disease (he survives). (Chapter 6, “Fighting Measles, Remodeling Society”) The eradication of smallpox has a long history. In 1721, the Congregationalist minister Cotton Mather of Boston introduces variolation, in which a bit of fluid from a smallpox boil is scratched into a patient’s skin, infecting him or her with a generally milder form of the disease. (Chapter 1; “Experimenting on the Neighbors”). In 1798, a rural English doctor, Edward Jenner, introduces smallpox vaccination using vaccinia, a virus grown on the underside of the cow. (Chapter 2, “The Peculiar History of Vaccinia”).

Tragedy: In 1901, smallpox vaccine contaminated with tetanus kills an estimated 90 children, mostly in the Philadelphia area, after manufacturers rush “green,” contaminated vaccine to market to fight a smallpox epidemic. This is one of many disease outbreaks linked to contaminated smallpox vaccine. Even when the vaccine is free of contaminating bacteria, it can be dangerous. In 1971, after a campaign led by Dr.C. Henry Kempe, pediatricians end the routine vaccination of American children against smallpox -- to prevent the estimated 10 deaths a year from the vaccine itself. (Chapter 3, “Vaccine Wars”; Chapter 6, “Battling Measles, Remodeling Society”)

2. Diphtheria

Triumph: In the 1890s, New York City bacteriologists William H. Park and Hermann Biggs begin administering diphtheria antibodies, grown in horses. Later, a combination of antibodies and diphtheria toxins are administered, allowing children to build a more robust immune response. Finally, in 1928 the city begins using diphtheria toxoid, made from deactivated diphtheria proteins. The disease once known as "childhood's greatest scourge," is nearly eradicated in the United States by the end of World War II. Outbreaks still sometimes strike in far-flung or medically weakened places, including several former Soviet republics in the 1990s, after soldiers from Afghanistan bring home a virulent form of diphtheria. (Chapter 4, “War is Good for Children”)

Tragedy: The use of antisera grown in horses and other animals creates a laboratory for immune system disorders. Horse proteins frequently cause serious reactions in children given diphtheria serum. The terms anaphylaxis, allergy and serum sickness are coined in the early 20th century to descibee the immune responses to foreign proteins contained in vaccines and sera.

3. Polio    

Triumph: Franklin Delano Roosevelt contracts polio in 1921, and three years later he purchases Warm Springs, a spa in Georgia, so that polio patients like himself could get decent occupational therapy in an atmosphere of fellowship. Roosevelt convinces his law partner, Basil O’Connor, to administer Warm Springs. O’Connor’s philanthropy, eventually called the March of Dimes, becomes the major source of funding for vaccine development. In 1955, Jonas Salk’s inactivated polio vaccine is licensed amid much jubilation. Five years later, a live, oral polio vaccine created by Albert Sabin at the University of Cincinnati comes on the market, and soon becomes the dominant vaccine. By early 2007, Sabin’s vaccine has nearly eradicated polio worldwide. The Western Hemosphere's last case of wild polio is reported in 1991.

Tragedy: Experimental vaccines developed by John Kollmer and Maurice Brody in the late 1930s cause hundreds of cases of polio. Shortly after the Salk vaccine is licensed, improperly inactivated vaccine causes a polio epidemic of its own, paralyzing about 200 people and giving thousands transient cases of the disease. Then scientists discover, in 1961, that the Salk vaccine had been grown in monkey kidney tissues contaminated with SV40, a virus that causes cancer in lab animals. Epidemiological evidence later suggests that the virus has caused few, if any, cancers in the children who received it. Sabin’s live vaccine causes about one case of polio for every million doses administered, usually affecting people with compromised immune systems.

4. Measles, Rubella and other Viral Vaccines

Triumph: Viral vaccines produce two Nobel prizes in the postwar era. The first goes to Max Theiler of the Rockefeller Institute for Medical Research in New York, who shows that when yellow fever virus is grown in a series of tissues, the virus loses most of its virulence and becomes suitable to use as a live vaccine. The second goes to John Enders, Frederick Robbins and Thomas Weller at Harvard University, who show it is possible to grow and attenuate viruses in tissue cultures–pieces of tissue from humans and various animals, pasted to the side of laboratory glassware. The work of Enders, Robbins and Weller facilitates Salk’s vaccine. Sam Katz, another Enders protegee, helps create a live measles vaccine by growing measles in human amniotic and chick tissues in 1954. Pharmaceutical companies make a variety of measles vaccines starting with this recipe. The maker of the Merck vaccine, Maurice Hilleman, goes on to attenuate mumps virus in a similar medium in 1965, and grows rubella virus in duck embryos, eventually creating the first measles-mumps-rubella, or MMR vaccine. Before these vaccines, measles struck about 3 million American children each year, killing or crippling about 10,000 kids every year. Rubella, which strikes in waves, left an estimated 30,000 children with severe birth defects during an epidemic in the mid-1960s. In 2002 and 2005, respectively, the Panamerican Health Organization declares that measles and rubella transmission has ceased throughout the Americas.

Tragedy: Yellow fever vaccine is a lifesaver, but difficult to make. In the early 1940s, scientists at the Rockefeller Institute find they need human serum to stabilize the vaccine. In early 1942, vaccine contaminated with hepatitis B virus is injected into 300,000 American troops, prostrating thousands of them in the months following Pearl Harbor. Many of the early measles vaccines are poorly made; two of the killed-virus vaccines, made by Pfizer and Lilly, respectively, are faulty because the inactivation process has damaged some of the measles proteins, resulting in “atypical measles”–-with severe allergic reactions and pneumonia--when the patient encounters the "natural" measles virus.

5. Whooping Cough

Triumph: Whooping cough has been one of the most severe and deadly childhood illnesses. Often fatal to infants, it produces a prolonged cough and shortness of breath for around three months, and sometimes causes permanent lung damage. In the 1940s, Pearl Kendrick and Grace Elderling at the Michigan Department of Health develop the first reliable whooping cough vaccine. Working with Margaret Pittman of the National Institute of Health, Kendrick develops tests for the efficacy and safety of this vaccine, made from killed pertussis bacteria. In the United States, whooping cough vaccines reduce what had been a devastating childhood illness, with thousands of deaths each year, to a far less severe threat. But immunity to whooping cough wanes, and many older people contract whooping cough–and spread it–without realizing they are sick with the disease. There are currently as many as 1 million cases of whooping cough each year in the United States–and at least 20 deaths.

Tragedy: While whooping cough vaccine has prevented more death and suffering than perhaps any vaccine currently in use, it has been devilishly hard to make reliably and safely. The whole cell vaccine is causes seizures, high fevers and rarely, permanent brain damage. Parents who believe their children have been damaged by the vaccine file many lawsuits in the 1980s. These suits threatened to drive vaccine makers out of the business until Congress in 1986 passes a law to compensate vaccine-injured children, while giving a measure of liability protection to manufacturers.

The Great Vaccine Debate

Autism is only the latest chapter.
Will it ever end?

The history of vaccination is criss-crossed with controversies. The allegation that vaccines cause autism is only the latest example. What is it about vaccines that attracts so much passion?

About the Book

Vaccine: the Controversial Story of Medicine’s Greatest Lifesaver relates the history of the development of vaccines–killed, weakened or fragmentary forms of a microbe that are injected or inhaled or ingested in order to produce immunity to the germ’s naturally occurring form. But Vaccine is more than a medical history, because the changes vaccination has wrought in society are profound. The story of vaccination also tells a lot about the human experience of modern times. It’s the saga of epidemics and how people faced them, the fear of God that disease once inspired, and the fear of the government that grows out of medical errors. It’s about what it’s like to live at a time when disease could suddenly sweep into your home and steal your child, and about the changing face of human faith at a time when infectious disease has, in great measure, been conquered, or at least tamed. It’s the story of the very human scientists–Pasteur, Salk, Sabin, Hilleman, and others—who dedicated their lives to assuring that families would never again be at the mercy of germs. It’s also about the struggle between personal autonomy and national goals, about allowing individuals to live their beliefs while still protecting the public health.

Other Articles by the Author

Arthur Allen’s published journalism includes hundreds of wire service and newspaper articles, 30 full-length magazine feature stories and more than 55 featured Web articles. He has also edited two book-length collections of investigative journalism, on water privatization and Latin American military affairs.

Kirkus Reviews

Allen’s clear, readable account describes the good that vaccines have done and the problems that vaccination faces. Solid, attention-holding history.

How to Think About Vaccination - My Perspective

As a child raised in the 1960s, I was shocked, as a new parent, when I read in 1996 that the CDC was recommending infants get a new, safer pertussis vaccine. They were also switching to a safer polio vaccine around that time. I thought to myself –safer? I had grown up thinking vaccines were as safe as milk. This was disconcerting information, and my sense of confusion is what ultimately led me to write a history of vaccination. The more I learned, however, the more I realized that the switch to new pertussis and polio vaccines was actually reassuring news. Like other newspaper-reading parents, I was learning about the potential dangers of vaccines in the 1990s because the authorities had stepped in to make them safer. We’ve all noticed, at some point in our lives, that no good deed goes unpunished, and this has never been truer than in the vaccination controversies that have broken out over the past decade.

The change in the old pertussis vaccine (the P in the DTP shot that also protects against diphtheria and tetanus) was a response, in part, to a grassroots protest movement that had led to a series of expensive lawsuits against the pharmaceutical industry. In 1986, Congress created a special no-fault court to compensate the rare child harmed by a vaccine. It also funded improved testing and monitoring of vaccine side effects. Both of these new programs made our national vaccination system safer. But because the government was now more aggressively dealing with vaccine problems, these problems became more visible. This was a better way of doing business than the old Big-Brother-knows-best way, but it had pitfalls, too. Now, parents could see all the warts and blemishes of the vaccine program. These disfigurations were much less common than in earlier times, but knowing about them made all the difference in terms of how people felt about vaccines. . The risks of vaccination had never been lower. But the risks were more visible than ever, the benefits hardly visible at all. Why? Because vaccines had done their job so well, the diseases they prevented were not high on the public’s radar.

The situation was almost exactly the inverse during the Baby Boom years. In March 1947, for the first time in 20 years, smallpox stalked the city of New York when a businessman named Eugene LaBar stumbled off a bus from Mexico City and died in a Midtown hospital, infecting a dozen other people before the authorities realized that he had been ill with smallpox. After posthumously diagnosing LaBar’s illness, the city ordered everyone to be vaccinated. Long lines stretched around the city as 6 million New Yorkers were voluntarily vaccinated within three weeks. As it turned out, smallpox had been contained before the vaccination campaign started, and the vaccines–which killed six people and made dozens sick–ended up doing more harm than smallpox did. No one complained, however. And that wasn’t the only vaccination disaster of the era. In 1944, a contaminated yellow fever vaccine infected 300,000 soldiers with hepatitis B as they mobilized for World War II. In April 1955, church bells rang as the entire country celebrated Jonas Salk’s new polio vaccine. But a few weeks later, bad batches of the vaccine killed 10 people and probably sickened as many as 70,000 others, in what became known as the Cutter incident, after the pharmaceutical company that produced most of the bad vaccine. In the 1960s, nearly a million kids were given a measles vaccine which, instead of protecting them when they were exposed to measles, often caused them to get dangerous cases of the disease.

You won’t find news accounts of the debacle of the 1947 smallpox vaccine campaign, or the early killed-measles vaccines. In the postwar era, the country was united in the fight against the infectious diseases that vaccines were fighting. People grew up knowing that polio could lock your son in an iron lung, that measles infection could turn your baby girl into a mental vegetable, that rubella, when it infected pregnant women, caused gruesome birth defects. People took their lumps, because the benefits of vaccination clearly outweighed the risks–they had watched in their lifetimes as  medicine slayed these child cripplers.

Today, all these diseases are rare in America, although they could easily return if we stop vaccinating. The absence of vaccine-preventable diseases is not back-fence news to parents–it’s hard to feel grateful for the disappearance of a horror you never experienced. Instead, parents mainly hear about injuries – real or perceived – caused by vaccines. And the government’s vigilance, when it comes to vaccine-caused injuries, reinforces this sense. In 1998, for example, the government stepped in to withdraw a new rotavirus vaccine–Wyeth’s Rotashield--that it linked to about a dozen cases of intussusception, a painful infantile bowel injury. That story was widely covered in the newspapers and television, which interviewed the parents of injured children. No one was making much of the thousands of U.S. kids hospitalized with rotavirus infection after the vaccine was shelved--or the hundreds of thousands who died of rotavirus each year in the Third World, and would have to wait longer for a vaccine.

The fact is, none of us really think about risks in a scientific way. The things that make us afraid aren’t the most threatening dangers. But there are certain rules of thumb about the kinds of things we tend to fear. We are more afraid of insidious, unseeable and rare dangers than the obvious ones. You’re more likely to drown in a bathtub than get eaten by a shark, but it’s the shark that lurks beneath the surface. Avian flu is no threat compared to hospital infections, but routine staph infections don’t breed in chickens in the mysterious Far East. Lack of control also breeds fear, which helps explain why people generally feel safer talking on a cell phone while speeding down a rush-hour freeway than they do sitting with tray tables in an upright and locked position on a commercial airliner. And we’re more likely to worry about chronic diseases like cancer and polio, which strike unpredictably and last for years, than the quick, deadly ones like pneumonia and heart attack. We are especially afraid of ailments caused by socially illicit acts or that produce strange behaviors–syphilis, schizophrenia, AIDS–or whose causes are unknown–think autism. Vaccines are especially likely to provoke irrational fear. You’re sticking a needle into a healthy baby, after all. Babies get sick, often, and they cry all the time. There’s a great likelihood that a baby will get sick sometime soon after getting a vaccination. When you get sick after a meal in a restaurant, you tend not to go back to that establishment–even if that steak you ate was well-cooked. Likewise, people whose kids got ill after a vaccine are likely to link the two. This helps explain the great appeal of the vaccines-cause-autism theory.

A year after the rotavirus problem, the vaccine authorities announced that they were asking manufacturers to remove the preservative thimerosal from the hepatitis B, Haemophilus influenza type B bacteria and DTP shots. This was a precautionary step based on the fact that a fully vaccinated child could receive as much as 187 millionths of a gram of ethyl mercury–an ingredient of thimerosal--over the first six months of its life, which might put the child’s blood mercury level above the EPA’s recommended threshold. The government acted although it hadn’t received any indication that thimerosal was hurting kids. The evidence of potential harm came from a study in Denmark. There, children whose pregnant mothers had eaten large amounts of whale meat containing methyl mercury–which was similar though not identical to ethyl mercury–seemed to score lower on certain tests of mental agility at age 7, though they did better in school. It was the theoretical harm from thimerosal, and the perception of harm, that led the government to act. Removing thimerosal was the right thing to do. But it backfired in a major way.

The government’s growing openness and vigilance about vaccine injuries coincided with the appearance of a new technology-- the Internet. Suddenly, people could get all the information they wanted about disease at the touch of a mouse. But the Internet did something weird to the instinctual math that we use for risk perception. Assume, for the sake of argument, that autism rates really haven’t changed in the past 20 years–assume that, then as now, roughly 1 in 200 people, or 1.5 million Americans, have autistic syndromes. Now if you had an autistic son born in 1986, you probably wouldn’t meet too many other autistics--how easy, pre-Internet, was it to meet 200 other people? Now, overnight, almost everyone was wired, and almost everyone with autistic children looked for answers on the Internet. Suddenly, the parent of an autistic child could instantly find tens of thousands of people in similar circumstances. Many people noticed their child’s problem shortly after a vaccination--at 9 months, or 12 months, or 18 months or whatever. Autism research has found that about a quarter of all autistic children’s symptoms follow this pattern–and have since long before thimerosal was an issue. But tell that to someone with an autistic child. Their doctor can’t explain what went wrong. And there are ten thousand other people on the Internet, in their family room, and they all agree that it was the vaccines. The Internet has created a huge, bitter echo chamber for people who desperately need explanations.

Has autism increased? It’s hard to know for sure. Although it is much more in the news than it ever was, autism is not a new disease. The Baltimore psychiatrist Leo Kanner was the first to define and coin the term autism in 1943, but hospital records from 19th century British asylums show kids with autistic symptoms, and there are other records of patients who clearly were autistic in the early 20th century, according to research by George Washington University anthropologist Richard Roy Grinker, who has an autistic daughter. One of the first attempts to find the rate of autism in the general population, a 1966 study by Victor Lotter in Middlesex County, England, found roughly 1 case of autism, as defined by Kanner, per 2000 children. When Lorna Wing conducted a study four years later in London she found a similar rate. Using an expanded definition of the disease, however, gave a number of 1 in roughly 400, she said. That did not include children who currently would be diagnosed as “on the spectrum.” In 1980, when a British hospital for the retarded was closed, nearly half of its discharged adult residents were determined to be autistic, though only a few had been previously diagnosed as such. In 1990, the Americans with Disabilities Act required states to report cases of autism in exchange for federal education funding. The numbers have steadily grown since then. But many of the experts who have been treating and studying autism for the past three decades are skeptical that the disease is actually on the rise.

For the many parents of autistics who do believe that autistm–and not just the reporting of it–has increased, vaccines are the number one culprit. A survey of parents at two autism treatment centers in New York and New Jersey in April 2005 found that 54 percent blamed vaccines for their child’s disease. For a while, this seemed like a plausible, if unlikely, idea. I wrote an article for The New York Times Magazine in 2002 saying thimerosal might explain some cases of autism. But since then, science has shown this isn’t so. Studies examining large populations of kids who received varying amounts of thimerosal as babies are indisputable: thimerosal had no impact on autism rates in the United States, England, Sweden, Denmark and Canada. The most convincing evidence comes from California, where the number of 3-to-5 year old children diagnosed with autism has doubled over the last five years, although children now being diagnosed with autism received little or no thimerosal-containing vaccines. Only two authors have found evidence linking thimerosal-containing vaccines and autism, and their studies are hardly worth considering. Mark and David Geier, a father and son pair with no academic affiliation or specific training in psychiatric illness (the son doesn’t even have a graduate degree), are attempting to establish their bona fides as autism experts so their testimony will be accepted in lawsuits against the pharmaceutical industry. They draw their evidence from a government database of voluntarily reported vaccine injury reports that has been skewed by reports filed at the insistence of personal injury lawyers with autistic clients.

No one disputes that thimerosal, like all mercury compounds, is potentially dangerous, at high doses. And some recent studies have shown that autistic kids might have metabolic disorders that put them more at risk from harm from toxic heavy metals like mercury. As with all toxins, however, the dose is the poison, and the amounts of mercury contained in vaccines pales by comparison to previous mercury uses. Crack open a medical text from the 18th century and you’ll find that calomel, or mercurous chloride, was a favorite medicine of the time. Doctors used this poisonous substance as a purgative, in accordance with the ancient medical philosophy of “balancing the humors” by inducing the patient to vomit, bleed, or evacuate his or her bowels. But while mercury caused many medical problems, in all the centuries of its use the substance was never linked to anything like autism. In much of the early 20th century, babies got Pink’s Disease, which included some neurological symptoms, after being fed a teething powder that contained calomel. But these children ingested up to two gram of mercurous chloride in a period of six months — 10,000 times more than the ethyl mercury any American child got through vaccination. And they did not become autistic. The average breastfed American infant gets twice as much organic mercury in mother’s milk as there was in vaccines. But no one says not to breast feed–on the contrary. It’s a question of balancing risks and benefits. Today, there is less thimerosal in American vaccines than there has been at any time since the 1940s. Some flu vaccines, which are given to kids at 6 months and up, contain 25 micrograms of thimerosal. That’s about the same amount of mercury as a can of tuna fish. Some parents blame their child’s autism on the measles-mumps-rubella (MMR) vaccine, but numerous careful studies have shown there is no connection.

Many fears of vaccines stem from conspiracy theories linking the pharmaceutical industry and government vaccine regulators. I like to think of myself as a critical and self-critical thinker.  I cut my journalistic teeth as a war reporter in the early 1980s, listening to U.S. and Salvadoran government officials lie about the things that soldiers were doing to El Salvador’s civilian population. I know that governments sometimes manipulate facts and that individuals are capable of evil. But these vaccine conspiracy theories don’t hold water. Much has been made, by vaccine critics, of a June 2000 meeting among government, industry and academic scientists outside Atlanta to discuss the possible damage caused by thimerosal in vaccines. The meeting, at which various experts expressed concern about thimerosal–and about lawsuits stemming from its use--wasn’t open to the press. But the same, initially troubling data released at that meeting was discussed a few weeks later at a very public CDC meeting. And while it is true that drug companies tried to use Congress to avoid lawsuits over thimerosal, you can’t blame them, considering the $300 million they’ve spent on the suits so far.

The more complex our world grows, the more each of us relies, like it or not, on the expertise of others. We also rely on our own biases. My father was an engineer, my mother an administrator at an adolescent health clinic. We had a lot of doctor friends (one of them lived on the same street with the brilliant and caustic Albert Sabin, inventor of the oral polio vaccine), and I have too much confidence in the honesty and good will of professional people to easily believe conspiracy theories. This framework of seeing the world is, no doubt, biased. So, it seems to me, are the criteria of the anti-vaccinists. When talking to one of the mothers I interview in my book – a woman whose daughter died of SIDS, more than a month after her last vaccinations–she told me that whenever the needle went into her daughter “it just seemed so wrong.” For this woman, the uneasy feeling she had at the time of her daughter’s vaccination represented a kind of mystical foreboding of the evil that would follow. She presented no other evidence that her child’s death was related to vaccines.  I suspect that many people who blame vaccines for their children’s problems were already uneasy about vaccines before they got them.

For the parents of autistics, vaccines can seem guilty by association simply because they are pushed by pediatricians. Parents who believe vaccines damaged their children will often include an anecdote spelling out how insensitive or unhelpful their pediatrician had been in diagnosing or treating the problem–as if the pediatrician’s inadequacies were somehow to blame for the disease itself.  A majority of these parents seek alternative healthcare to help cure their kids. Whether the alternatives cure or not, people seek them because mainstream medicine lacks the answers. And it so happens that the same people who are offering alternative therapies for autism are also offering alternative explanations. Alternative medicine has a long history of opposition to vaccination.

The thimerosal theory has gradually gotten harder to defend. But science can never prove that a given person’s problem has a particular cause. “Well, maybe it doesn’t always cause autism,” some parents tell me, “but it did it to my kid.” And there’s no way to prove them wrong. Others worry that all the shots in the new vaccine schedules “overwhelm” a child’s immune system, although children receive fewer antigens from vaccines than they did 20 years ago. A typical infection, whether it be from flu or rotavirus or the common cold, contains billions more infectious particles than all the vaccinations combined.

Jim Cherry, a DTP expert, says that parents who don’t vaccinate tend to be “people who know too much but not enough.” While it’s an unkind statement, I think it’s accurate. If you start to dig, you may become alarmed. If you dig enough, and you aren’t biased, you’ll conclude that on balance vaccines are pretty safe and that they’ve done wonderful things.

The problem with the growing number of vaccine skeptics in the U.S. is this: a single parent may make a calculated risk not to vaccinate their child, and escape unscathed. After all, polio is pretty much vanquished around the world, measles is rare in the United States, and whooping cough doesn’t usually kill your kids, though it may make them very sick. But if too many parents who know better make the decision not to vaccinate, it will poke holes in the network of protection that decades of vaccination have built up in this country through herd immunity–the more people who are vaccinated, the safer our “herd,” as the germs find fewer bodies in which to grow and spread. Considering the amount of dedicated time and effort that have gone into this lifesaving measure, that would be a terrible thing. So listen to your pediatrician’s advice. Unless you have a really good reason not to, vaccinate.