WASHINGTON — Recently I wrote about a type of scientific denialism — often practiced by religious people — that cheats children out of the wonders of modern cosmology and encourages unnecessary religious doubt. But there is another sort of scientific skepticism — often displayed by affluent and educated parents — that withholds routine childhood vaccinations and encourages unnecessary disease.
These should be kept in proportion. The belief that human beings walked with dinosaurs is wrong. The belief that vaccinations cause autism or brain damage is wrong and dangerous.
In the latter case (as in the former) the scientific argument is not merely lopsided but single-sided. Like any medicine, vaccines have a very small risk of serious side effects, which doctors are trained to identify. But the association of measles vaccination with autism is entirely discredited. Childhood vaccinations do not involve dangerous levels of toxins and do not compromise the immune system. And vaccinations prevent a range of diseases — chickenpox, diphtheria, measles, mumps, pertussis, polio, rotavirus, rubella, tetanus — that used to routinely hospitalize, disable or kill children.
In most health matters, defying medical authority mainly has individual consequences. Those who believe that cancer can be treated with coffee enemas are only killing themselves. But communicable diseases are different. Some people can't be immunized for medical reasons, or their protective response to a vaccine is weak. They depend on the immunity of others to avoid infection. Immunization rates north of 90 percent are usually required to protect the whole herd.
This means that if even a small portion of the herd refuses vaccination, the risks rise for everyone. Epidemiology grants marginal groups the power to do great harm. America generally has rates of immunization in the high 80s or low 90s. In some places, however, the rate dips lower, making it easier for an infected traveler (for example) to cause an outbreak. Recent examples can be found in Orange County, Calif., and New York City. The problem is even worse in Britain (where the immunization rate for measles is only about 80 percent) and in other parts of Europe.
Those who resist vaccination are a varied group. The parents of autistic children seek and deserve an explanation. Unfortunately, vaccination is not the answer. Other "non-conformists" are a subset of homeschoolers, distrustful of government mandates and intent on the right to keep and bear viruses. A larger number of resisters are committed to an organic, chemical-free, natural lifestyle. This is attractive, except on diseases when the "natural" state — through most of history and still in much of the world — has been massive infant and child suffering and death. The achievements of science in this area are highly artificial — and thank goodness.
The ability to opt out of vaccinations (other than for diagnosed medical problems) is often miscast as a matter of parental choice, leading to a proliferation of state exemptions for vague religious and philosophic reasons. What could be wrong with choice? A lot, when you are choosing to endanger your neighbors. Vaccination — in a little-used but useful term — is a social responsibility. It is a duty we owe each other as members of a community. Opting out should be difficult and burdensome. And there is no parental right to send a purposely unvaccinated child to public school, exposing other children to unnecessary risk.
Resistance to immunization is not new. In the late 1700s, some believed that the smallpox vaccine could turn people into cows. Today, however, there would be 1,000 websites alleging a sinister connection between Big Pharma and Big Dairy. The problem of vaccine denialism is closely tied to the problem of information and authority in the digital age. People prone to skepticism can cover themselves with layers of pseudo-science and conspiracy theories that thicken and harden like papier-mache.
On medical issues, America needs not more sources of questionable information but more trust in knowledgeable authority. The Centers for Disease Control and Prevention, the American Academy of Pediatrics and your local pediatrician are not lying about immunization. Many websites are.
The seriousness of this discussion must somehow reflect the seriousness of the stakes. Vaccine denialism is not the equivalent of advocating for diaper-free children or sleeping in the family bed. During the lifetimes of American children born from 1994 to 2013, according to the CDC, childhood vaccinations will prevent an estimated 21 million hospitalizations and 732,000 deaths. Which is miraculous, but not natural.
Michael Gerson's email address is email@example.com.