Feb. 4, 2001

REFUSING CHILDHOOD IMMUNIZATION IS RISKY

Two Denver-area children died of influenza in January, and for a heart-stopping moment parents were reminded that not so very long ago, children's lives were fragile and often brief.

Immunization against childhood diseases now prevents many deaths and an untold number of serious, debilitating illnesses. Yet some parents worry more about the risks from the immunizations than they do about the risks from the diseases the immunizations avert.

Parents may feel they are playing Russian roulette with the lives of their children, whichever choice they make, and in the sense that no one can predict who will react badly to a generally safe vaccine or which unvaccinated child will fall seriously ill, that's true. But parents should realize that if they deny their children immunization, they are deliberately leaving more bullets in the gun.

Colorado has relatively relaxed laws concerning immunization. Though the law requires parents to have their children immunized before they start school, it allows exemptions for medical or religious reasons, as almost all states do.

And it's one of only 15 states that also allow exemption for "philosophical" reasons.

A study of Colorado's exempt children published in the Dec. 27 issue of the Journal of the American Medical Association compares their rates of measles and pertussis (whooping cough) with those of immunized children. The results for children 3 to 18: exempt children were 22 times more likely to get measles and six times more likely to get pertussis.

The study's lead author is Daniel Feikin of the federal Centers for Disease Control and Prevention. Co-authors include Dennis Lezotte and Richard Hamman of the University of Colorado Health Sciences Center and Richard Hoffman of the Colorado Department of Public Health and Environment.

"As the frequency of vaccine-preventable diseases has decreased, fewer persons have ever witnessed a child who is severely ill with a vaccine-preventable disease," the authors write. "As a result, parents today might perceive a greater risk in having their children vaccinated than in not having them vaccinated."

The number of Colorado children exempted for medical reasons is tiny, 891 in 1998, and the rate (0.12 percent) is nearly constant over the last decade.

The rate for religious exemptions is also small, 0.18 percent, and it has been declining. But the number choosing exemption for philosophical reasons is 10 times higher than that, and at 13,991 it has more than doubled since 1987.

Hoffman emphasizes that these are contagious diseases. So parents who refuse immunization are putting not only their own but other children at risk. The researchers calculated that for each 1 percent increase in the number of exempt children in a school, the risk of a pertussis outbreak rose by 12 percent.

And since vaccines are effective but not perfect, even children who have been vaccinated against a disease are more likely to contract it as the number of unvaccinated children rises. At least 11 percent of vaccinated children in measles outbreaks caught it from an exempt child.

Severe side effects from the new diphtheria-tetanus-pertussis vaccine used since 1997 are extremely rare, around 25 per 100,000, and permanent consequences virtually unknown. (Never say "never," Hoffman cautioned.) In contrast, from 1996 through 1998, 3-to-5-year-old exempt children contracted pertussis at a rate of 191 per 100,000, compared with 11 per 100,000 for vaccinated children.

In 2000, Hoffman said, there were 476 cases of pertussis in Colorado, the most in any year since 1963. Two infants died. They were less than two months old, too young to have been immunized themselves, but it appears they caught the disease from older siblings who were not protected.

I wouldn't argue for the repeal of the philosophical exemption.

Philosophical views may be held every bit as tenaciously as religious ones, and deserve as much respect. Also, parents may wish to make distinctions among the long list of immunizations that are recommended, which is not possible if they claim a religious exemption.

But I would urge every family that may be considering exemption to evaluate the scientific evidence and not lightly expose their children and others' to unnecessary danger.

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