CHICAGO Children who for religious or other reasons do not get vaccinated against measles or whooping cough are more likely to contract the illnesses and spread them to vaccinated classmates, a study said on Sunday.

An 11-year study of Colorado schoolchildren ages 3 to 18 found a much higher rates of measles and whooping cough, or pertussis, among unvaccinated children -- especially among the youngest.

Measles rates were 22 times higher and whooping cough rates were six times higher in unvaccinated children than in youngsters who received the vaccinations, said the report from the U.S. Centers for Disease Control and Prevention in Atlanta.

The comparative rates tripled among unvaccinated children ages 3 to 10.

Most states grant exemptions from mandatory childhood vaccinations on religious grounds and some grant them on philosophical grounds, the report said.

An increasing number of parents are less concerned about having their children vaccinated because of the rarity of these childhood illnesses.

Many are aware of media reports and warnings from anti-vaccine groups that the vaccines themselves might pose dangers to their children, such as autism, seizures or diabetes.

Based on data from 1994, about six out of 1,000 U.S. children were unvaccinated. In Colorado, 14 out of 1,000 children were not vaccinated that year.

Unvaccinated Children Put Others at Risk

Besides putting themselves at risk, unvaccinated children were more likely to attend schools where outbreaks of the illnesses occurred, the report appearing in last week's Journal of the American Medical Association said.

It estimated that more than one in 10 children vaccinated against measles contracted the infection through contact with a vaccine-exempt child.

"If all vaccine-preventable diseases were confined to the individual (as with tetanus), the consequences of forgoing vaccination would fall only on the child whose parents made the decision," study author Daniel Feikin wrote.

"Most vaccine-preventable diseases, however, are spread from person to person. Therefore, the health of any individual in the community is intricately dependent on the health of the rest of the community," he wrote.

But an editorial in the journal by Kathryn Edwards of Vanderbilt University in Nashville, Tennessee, said each state must assess the severity of childhood illnesses and the safety and efficacy of vaccines designed to prevent them before requiring immunizations.

"Vaccines remain the most important strategy to prevent infectious disease in children. We must use our mandates wisely," Edwards wrote.

(Reuter)