Educating Teens About Vaccines

Tetanus, diphtheria, and acellular pertussis vaccine 

In 2004, the number of reported pertussis cases reached 25,827; the highest reported cases in 1 year. Of those reported 25,827 cases, a total of 8897 (34%) of the reported US cases occurred among adolescents aged 11 to 18 years (incidence for adolescents, 30 per 100,000 population); 17 states reported more than 100 pertussis cases in adolescents (American Academy of Pediatrics Committee on Infectious Diseases, 2005).

One explanation for this increased incidence of pertussis among adolescents is waning vaccine immunity, suggesting that adolescents and adults were carriers of Bordetella pertussis and, therefore, were responsible for the resurgence of pertussis in the United States. Complications such as pneumonia, seizures, encephalopathy, and death are associated with pertussis in infants. Out of the of the 103 reported pertussis fatalities between 1990 and 1996, 99% were infants (Guinto-Oampo, McNeil, & Aronoff, 2006).

On May 5th, 2005, the Food and Drug Administration (FDA) approved tetanus toxoid, reduced diptheria toxoid, and acellular pertussis (adolescent preparation) (Tdap), a new tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis vaccine for adolescents. The American Academy of Pediatrics’ newly released 2006 immunization schedule recommends a single dose of an adolescent preparation of Tdap between 11 and 12 years of age for those who have completed the recommended diptheria toxoid, tetanus toxoid, and pertussis/diptheria toxoid, tetanus toxoid, and acellular pertussis (DTP/DTaP) series and have not received a tetanus-diphtheria booster. “Also, adolescents aged 13 to 18 who have missed the 11- or 12-year-old tetanus-diphtheria or Tdap booster or in whom it has been 5 years or more since the tetanus-diphtheria booster dose also should receive a single dose of Tdap if they have completed the DTP/DTaP series” (American Academy of Pediatrics Committee on Infectious Diseases, 2006).

There were two Tdap adolescent immunizations that were approved by the FDA in 2005. The first, Boostrix, is manufactured by GlaxoSmithKline and is approved for use in children 10 to 18 years of age. The other Tdap immunization is Adacel, which is manufactured by Sanofi Pasteur and has been approved for use in individuals 11 through 64 years of age. The newly recommended Tdap immunization guidelines should impact the incidence of pertussis infections among adolescents and adults and indirectly protect those infants who are too young to have completed their primary immunization series (Humiston & Rosenthal, 2005).

Meningococcal vaccine 

“Every year in the United States, approximately 1400–2800 individuals are infected with invasive meningococcal disease. Neisseria meningitis has become the leading cause of bacterial meningitis in the United States. Death occurs in 10% to 14% of individuals with meningococcal disease and 11% to 19% percent of those who survive have permanent disabilities, such as mental retardation, hearing loss, and loss of limbs” (ACOG Committee on Adolescent Health Care, 2005). Approximately, 75% of cases of invasive meningococcal disease that occur in adolescents are caused by meningococcal serogroups: A, C, Y, and W-135. The greatest incidence of invasive meningococcal disease occurs in infants who are less than 1 year of age and adolescents 15 to 18 years of age. Although the incidence of invasive meningococcal disease is greater in infants, mortality is higher in adolescents (20%) (American Academy of Pediatrics Committee on Infectious Diseases, 2005).

In 1981, Menomune (MPSV4), a tetravalent polysaccharide vaccine manufactured by Aventis Pasteur, was licensed for use in individuals 2 years of age and older. This vaccine provides a T-cell–independent immunity that results in poor long-term immunity (<3 years). The MPSV4 vaccine does not induce herd immunity or reduce nasopharyngeal carriers of Neisseria meningitis (Cohen, Broder, & Pickering, 2005). The MPSV4 vaccine only protects against two thirds of the meningococcal disease in adults. Therefore in 2005, the FDA approved quadrivalent meningococcal conjugate vaccine (MCV4; Menactra, SanofiPasteur) for use in adolescents and adults 11 to 55 years of age. MCV4 induces T-cell–mediated immunity; the duration of protection is approximtely 8 years, considerably longer than that of MPSV4. The CDC recommends that MCV4 be given to adolescents 11 to 12 years of age. Those previously not vaccinated at 11 to 12 years of age should be vaccinated before they enter high school at around 14 years of age and any adolescent between the ages of 11 to 18 years should be vaccinated. Many colleges are now requiring this immunization prior to admission.

Hepatitis B vaccine 

Hepatitis B (HBV) is transmitted from one person to another through blood and body fluids and primarily affects the liver. Worldwide, it is most commonly spread to infants by their infected mothers. An estimated 1.25 million people in the United States have chronic HBV. Each year, approximately 4000 to 5000 children are infected with HBV in the United States. The most effective way to prevent transmission of HBV is by immunization. Hepatitis B–infected individuals are at greater risk of developing cirrhosis and hepatocellular carcinoma and can transmit the virus to others through sexual contact, sharing of needles, or fetal transmission. Hence in, 1991 HBV vaccination became part of the recommended vaccine schedule for children.

However, in a 2004 CDC report, only 50% to 60% of adolescents aged 13 to 15 years had records indicating vaccination with 3 doses of vaccine against hepatitis B. The Advisory Committee on Immunization Practice’s report of 2005 provided new recommendations to improve prevention of perinatal and early childhood HBV transmission. One strategy mentioned was to review immunization records of all children aged 11 to 12 years and children and adolescents less than 19 years of age. Another strategy was the adoption of hepatitis B vaccine requirements for school entry. As of November 2005, a total of 34 states require vaccination for middle-school entry (Morantz, 2006).

The current 2006 recommendation is that all unvaccinated children and adolescents less than 19 years of age should receive the HBV vaccine series. There are two single-antigen HBV vaccines currently available in the United States: Recombivax HB (Merck & Co., Inc., Whitehouse Station, NJ) and Engerix-B (GlaxoSmithKline Biologicals, Rixensart, Belgium). The HBV vaccine 5-μg dose for adolescents should be administered intramuscularly on a 0-, 1-, and 6-month schedule to produce 95% sero-protection against the hepatitis B virus. There is also a 2-dose schedule of Recombivax HB (10-μg adult dose), which can be given to adolescents aged 11 to 15 years on a 0-, 4-, or 6-month schedule for protection against HBV (Yu, Cheung, & Keefe, 2006).

Human papillomavirus vaccine 

Human papillomavirus (HPV) is a sexually transmitted infection, which affects millions of men and women worldwide. More than 35 types of HPV are known to infect the genital tract (Bonnez 2005, Harper et al 2004, Villa et al 2005). Types 16 and 18 cause about 70% of cervical cancer and cervical intraepithelial neoplasia, and types 6 and 11 cause 90% of genital warts in both men and women (Arvin & Greenberg, 2006; Bonnez 2005, Centers for Disease Control and Prevention 2006a, Harper et al 2004, Villa et al 2005). HPV infection causes approximately 470,000 cases of cervical cancer worldwide each year (Harper et al 2004, Villa et al 2005). Cervical cancer is the second most common cancer in women, making this disease a major public health problem (Bonnez 2005, Centers for Disease Control and Prevention 2006a).

The majority of cases of HPV are acquired within 5 to 7 years of the onset of sexual activity. Research has shown that 37% of males and 28% of females are sexually active by the ninth grade and 7% of adolescents are sexually active before age 13 (Bonnez 2005, Olshen et al 2005, Zimet 2005). Thus, exposure to a potentially fatal disease occurs at increasingly younger ages.

To combat the devastating effects of HPV, two vaccines targeted to pre- and early adolescents have been developed. Merck’s quadrivalent HPV vaccine, which offers protection against the most carcinogenic HPV strains, types 6, 11, 16, and 18, called Gardasil, was approved by the US Food and Drug Administration (FDA) on June 8, 2006 (FDA, 2006a). A bivalent HPV vaccine that will protect teens against HPV types 16 and 18 is in phase III clinical trials. GlaxoSmithKline is expected to receive FDA approval for this vaccine, Cervarix, in late 2006 (Bonnez 2005, Williamson et al 2005).

FDA approval for Gardasil came after four successful phase II and III clinical trials evaluating the safety and efficacy of this vaccine. These trials concluded that vaccination with Gardasil—prior to natural exposure to HPV types 6, 11, 16, and 18—provided females with greater than 99% immunity to these HPV types (Bonnez 2005, Food and Drug Administration 2006a, Food and Drug Administration 2006b, Villa et al 2005, Williamson et al 2005). The duration of immunity provided by this vaccine has yet to be established by long-term studies. In phase III of these studies, recipients received a three-dose series of Gardasil over a 6-month period, followed by antibody testing 1 month after the last injection. These trials included 8915 females ranging in age from 9 to 26 years. There were no significant deviations in immunity among different age groups (Food and Drug Administration 2006a, Food and Drug Administration 2006b). The most commonly reported adverse events include injection site pain, swelling, erythema, pruritis, and fever. Less than 1% of study participants discontinued the vaccine owing to adverse events (Food and Drug Administration 2006a, Food and Drug Administration 2006b; Villa et al.).

Based on these findings, the FDA has approved use of Gardasil in females aged 9 to 26 years for the prevention of end diseases of HPV infections, including cervical cancer and genital warts (Food and Drug Administration 2006a, Food and Drug Administration 2006b). Gardasil is not recommended for use in pregnant women, and should be used with caution in patients with immunosuppression. This vaccine should be administered intramuscularly in three separate 0.5-mL doses, with the second dose 2 months after the first, and the third dose 6 months after the first. Gardasil has also been approved for concomitant administration with hepatitis B vaccination, at separate sites (FDA, 2006b).

Large-scale phase III clinical trials are currently underway for Cervarix. Phase II clinical trials of the bivalent vaccine have shown great promise in preventing HPV and sequalae. The bivalent vaccine has been shown to prevent cervical cancer and CIN in more than 93% of vaccinated women. This protection has been demonstrated to extend as far out as 4.5 years after vaccination (Bonnez 2005, Centers for Disease Control and Prevention 2006a, Harper et al 2006, Williamson et al 2005). Only mild to moderate side effects have been reported with this vaccine. More than 94% of women reported injection-site pain and/or headache as the only adverse events, and no participants were reported to have withdrawn from the trials because of these events (Bonnez 2005, Harper et al 2004, Harper et al 2006).

Among the questions yet to be answered about these vaccines is their safety and efficacy in males. Thus far, most of the clinical trials have taken place in women, so little is known about what effect the HPV vaccines will have in preventing the spread of the disease in men. Researchers have speculated that the vaccines will be as efficacious in preventing genital warts and HPV spread in males as in females. Currently, Gardasil has been approved for use only in females. It is likely that, once approved, the bivalent vaccine will also be available only to females. It is possible, however, that these vaccines will later be approved for use in males in order to prevent the spread of HPV (Centers for Disease Control and Prevention 2006a, Dempsey et al 2006).

Much of the research surrounding the HPV vaccine has focused on parental attitudes and acceptance. Because the HPV vaccines will likely be recommended for the 10- to 12-year age group, parental consent will be required. Some of the factors that have been found to influence parents’ willingness to vaccinate their children against HPV include parental knowledge about the disease, age at administration of the vaccine, and fear of an increased risk of early sexual activity because of the vaccine (Dempsey et al 2006, Olshen et al 2005, Zimet 2005).

Many parents are unfamiliar with HPV. Health care providers have a responsibility to increase parents’ and adolescents’ knowledge about this disease, and the positive and negative aspects of the vaccine. One recent study found that parents’ understanding of HPV was increased when their health care provider gave them a 1-page information sheet about the disease and the vaccine. This increased knowledge, however, did not increase the parents’ likelihood to consent for their child to receive the vaccine (Dempsey, Zimet, Davis, & Koutsky, 2006). Thus, information alone is insufficient for parental acceptance of an HPV vaccine.

Some parents were reluctant to consent to an HPV vaccine in their younger adolescents because they felt the choice should belong to the child. These parents advocated waiting until the child was of age to consent for their own treatment (Olshen, Woods, Austin, Luskin, & Bauchner, 2005). The American Academy of Pediatrics encourages health care providers to include adolescents in their own care. However, it should be emphasized that the HPV vaccine is only effective in preventing transmission of the virus, not in treating the resulting medical conditions. Therefore, it is necessary to vaccinate prior to the onset of sexual activity. Parents need to be aware that waiting to vaccinate their adolescent until they can consent places them at increased risk of contracting HPV if they are sexually active. It is advisable to receive parental consent and adolescent assent for this vaccine.

Similarly, parents expressed concern that receiving a vaccine to prevent an sexually transmitted infection would encourage adolescents to be more promiscuous and to practice unsafe sex (Dempsey et al 2006, Olshen et al 2005, Zimet 2005). There has been no evidence to date to show that strategies to prevent the spread of any sexually transmitted infection increases sexual activity. Parents and teens need to be made aware that this vaccine protects against only one infection and that there are numerous other consequences to unsafe sex, including infection with human immunodefinciency virus and other sexually transmitted infections, as well as unwanted pregnancy (CDC, 2006a). Anticipating parents’ and adolescents’ concerns regarding these and other issues with regard to the HPV vaccines will help the health care provider lead clients to informed decisions. With these and other vaccines directed toward adolescents health care providers should emphasize the opportunity that parents have to protect their children now and into adulthood.

Measles, mumps, rubella, and varicella combination vaccine 

Varicella is a highly contagious viral infection. Though formerly considered a childhood rite of passage, varicella is a dangerous disease that caused anywhere from 47 to 138 deaths per year prior to the availability of the vaccine (Nguyen, Jumaan, & Seward, 2005). In 1995, varicella became a vaccine-preventable disease, and by 2000, the incidence of disease had decline by 71–84% (Nguyen, Jumaan, & Seward, 2005). Yet, despite the evidence that the varicella vaccine is safe and effective, only approximately 84% of children in the United States receive the vaccine. This is in contrast to the 93% of children who have been vaccinated against MMR, a vaccine administered at the same time as the varicella vaccine (Shinefield et al., 2005b).

Though research has yet to identify a clear reason for under-immunization against varicella, there is evidence to suggest that a quadrivalent vaccine might improve compliance by decreasing the number of injections given to children (Shinefield et al., 2005b). Research to produce a combined MMR and varicella vaccine has been underway since the late 1980s. Researchers have already confirmed that it is safe and efficacious to administer both the MMR and varicella vaccines concomitantly at separate injection sites (Nolan et al 2002, Shinefield et al 2002). These studies found equivalent rates of immunogenicity to each of the diseases as when the vaccines were administered on separate occasions (Nolan et al 2002, Shinefield et al 2002).

Subsequent research examined the possibility of using a combination vaccine based on the MMR and varicella vaccines already in use. Initial studies failed to demonstrate as high a rate of seroconversion to varicella with a combined MMR + varicella (MMRV) vaccine as with the varicella vaccine given separately, though they did establish an equivalent safety profile (Nolan, McIntyre, Roberton, & Descamps, 2002). Recent research, examining the effect of increasing the dose of the varicella component in a combine MMRV vaccine, has demonstrated great improvement in the immunogenicity to varicella. These studies show that vaccination with a higher-dose varicella MMRV is immunologically comparable to separate administration of MMR and varicella vaccines (Knuf et al 2006, Shinefield et al 2005a, Shinefield et al 2005b). Shinefield et al. (2005b) also demonstrated that a second dose of MMRV boosts immunity to varicella further, thus decreasing the likelihood of breakthrough disease. The adverse event rate is also similar, with rash and high fever being reported slightly more frequently in children who receive the MMRV versus MMR and varicella separately. Overall, however, the MMRV vaccine is generally well tolerated (Knuf et al 2006, Shinefield et al 2005a, Shinefield et al 2005b).

In September of 2005, the FDA approved Merck’s Proquad, a quadrivalent MMRV vaccine. Shortly thereafter, the CDC Advisory Committee on Immunization Practices released its recommendations for administration of the MMRV vaccine, stating that MMRV may be used in place of the first doses of MMR and varicella at or after age 12 months. In children less than 13 years of age, the second dose of MMRV is to be given no less than 4 weeks later. In the event of a varicella outbreak, a second dose of MMRV may be given no less than 3 months after the first dose. In children more than 13 years of age, a second dose of varicella is recommended. A second MMRV may be given to children more than 13 years of age no less than 4 weeks after the first dose. Contraindications to the MMRV are the same as for each of the individual components. These include allergy to vaccine components, moderate or severe febrile illness, pregnancy or breastfeeding, immunodeficiency, recent receipt of blood products, high-dose steroid use, use of salicylates, and exposure to others who are immunocompromised (Centers for Disease Control and Prevention 2005a, Centers for Disease Control and Prevention 2005b).

Conclusion 

Pediatric healthcare providers should consider these recommendations and research when determining which vaccinations to use in their practice. It is clear that under-immunization is a serious problem. This problem can be addressed through consistent efforts to educate parents and teens about available vaccines, their safety, and effectiveness. FIGURE 1, FIGURE 2 provide vaccine information on the Tdap and HPV vaccines to assist in this important responsibility of pediatric health professionals. Cohen et al 2005, Committee of Infectious Diseases 2006, Yu et al 2006Arvin and Greenberg 2005

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FIGURE 1. Information on the Tdap vaccine.

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FIGURE 2. Information on the HPV vaccine.