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Pediatric Update

 
Spring 2008

New Vaccines Must Be Given Universally to Benefit Public Health

04/24/2008

The recent approval of several new vaccines for children and adolescents promises to bring major public health benefits—but only if they are universally applied, says James Cherry,M.D.,UCLA pediatric infectious diseases expert.

Highly effective shots are now available to inoculate against human papillomavirus (HPV); rotavirus; meningitis; tetanus, diphtheria and pertussis; and, now in combination, measles, mumps, rubella and varicella (MMRV). But some fail to appreciate the importance of achieving herd immunity— in effect, eliminating the diseases from the population—by ensuring that the vast majority of patients receive the vaccines.

“The reason we have been successful against diseases such as measles, mumps, rubella and polio is that we’ve been able not only to immunize individuals but to reach enough of the population that we create herd immunity so that the disease can’t circulate and find those who aren’t immunized,” Dr. Cherry notes.

Reaching a critical mass of the poulation is particularly challenging when it comes to shots for older patients, such as adolescents and adults, many of whom tend to have weak ties to the healthcare system, Dr. Cherry says. Compounding the problem are misconceptions about the risks associated with available vaccinations. Most prominent among these is the well-publicized concern that MMR and thimerosal are linked with increased autism risk, despite the absence of any credible scientific evidence to support the claim and numerous studies that have refuted it.

“A number of parents are coming in with misinformation, and it’s up to pediatricians to be persistent in explaining that these vaccines are safe and important,” Dr. Cherry says. He suspects that many of those who are not forceful enough in pushing for the vaccines are too young to have seen firsthand the havoc caused by the likes of bacterial meningitis, polio, measles, rubella and mumps.

Among the most promising of the new immunizations is the HPV vaccine, which has been approved by the Food and Drug Administration (FDA) to prevent cervical cancer and genital warts in females ages 9 to 26 years and is recommended to be routinely given to girls at age 11 or 12 years, prior to the onset of sexual activity. The vaccine contains the serotypes that cause up to three-fourths of cervical cancers and roughly the same proportion of genital warts, Dr. Cherry notes, and large studies have shown no significant side effects.

Within the next two years, the recommendation for boys will be the same as that for girls—a critical step toward the goal of herd immunity, Dr. Cherry notes. Although there has been some political resistance to the shots, particularly among people with a moral objection to a vaccine for a sexually transmitted disease, it appears that the greater challenge is reaching adolescents and pre-adolescents who aren’t regularly seen in the healthcare system.

The rotavirus vaccine, which is recommended for infants, protects against an infection that is the most common cause of severe dehydrating diarrhea in babies and young children, and is estimated to be responsible for 500,000 physician visits and tens of thousands of hospitalizations in the United States each year. Because rotavirus-caused diarrhea tends to be less severe in more affluent populations, some physicians fail to push the vaccine, Dr. Cherry says. “The fact is that it works, it will decrease rotavirus disease substantially—possibly even achieving herd immunity—and the cost saving from hospital admissions will be tremendous,” he asserts.

Menactra, which protects children from several strains of meningococcal bacteria—including the leading cause of bacterial meningitis in adolescents — is recommended to be given routinely to all 11-year-olds. But thus far, a low percentage of eligible patients has received the shot. “The vaccine prevents a terrible disease, which can cause long-term disabilities or death,” Dr. Cherry says.

The new Tdap vaccine, which combines vaccines against tetanus and diphtheria with the acellular pertussis vaccine, is also recommended for all pre-adolescents, and can be given at the same time as Menactra and, for girls, the HPV vaccine. Adherence to this recommendation is also low, though Dr. Cherry hopes that will soon change. Pertussis is common in teens and adults in the United States; it is also highly contagious, and when transmitted from adults to infants the consequences can be particularly severe. “For herd immunity, we will have to immunize adults at periodic intervals as well as adolescents,” Dr. Cherry notes.

As for the new MMRV vaccine, which combines MMR and a varicella vaccine into one shot, Dr. Cherry says it is not vital that patients receive the four-type shot, but everyone should be given MMR and V, whether together or separately. “The circulation of measles and rubella has been eliminated in this country thanks to continued vigilance in immunizing the population,” he notes. “We have had mumps outbreaks the last two years, so we need to work harder at getting patients second doses of that vaccine, since the vaccine is not quite as effective. And anywhere varicella vaccine has been used, there has been a marked reduction in the number of cases.”

All things considered, Dr. Cherry believes most pediatricians do an excellent job in ensuring that their patients receive the appropriate immunizations. “It’s not always easy given the misinformation that’s out there,” he says, “but we must continue to work hard at this. The consequences if we don’t are too severe.”

Recommended Reading

Immunization Action Coalition
www.immunize.org

Centers for Disease Control and Prevention
www.cdc.gov/vaccines

Parents' Guide to Childhood Immunizations
www.cdc.gov/vaccines/pubs/parents-guide/default.htm





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