Immunization of adolescents: reaching a forgotten population

March 2002

Each year the Recommended Childhood Immunization Schedule endorsed by the AAP, ACIP and AAFP is revised. The schedule for 2002 includes several changes over last year (see PDF chart).

Included in the new schedule is a “preadolescent assessment,” and specially shaded immunizations that are meant to highlight “age groups that warrant special effort to administer those vaccines not previously given.” The 11- to 12-year age group is shaded, as this age has been identified as a convenient time when pediatricians can assess an adolescent’s need for recommended immunizations.

The Advisory Committee on Immunizations Practices (ACIP), along with the AAP, the American Academy of Family Physicians (AAFP) and the American Medical Association have previously published recommendations on adolescent immunization requirements. While the immunization schedule mostly targets young children, adolescents cannot be ignored, as risk for some infections (eg, hepatitis B) increases substantially in adolescence. Because of this increased risk, and partially because of an increased potential for age-related adverse outcomes with some infections (eg, varicella), it is important for pediatricians to screen adolescent patients for immunization deficiencies.

The recommendations on adolescent immunization published in 1996 by the CDC call for the establishment of routine health care visits for children age 11-12 to screen and provide immunizations that may not be current. These recommendations specify screening for immunization for hepatitis B (HepB), varicella (Varivax, Merck), the second dose of measles-mumps-rubella (MMR, M-M-R II, Merck) and tetanus-diphtheria booster (Td). Depending upon specific risk factors, other immunizations may be warranted (eg, hepatitis A).

Most people in the United States infected with hepatitis B virus (HBV) are exposed during adolescence or as a young adult. Although HepB immunization is routinely recommended, it is especially important to check the status of this immunization at 11-12 years of age, prior to the potential for initiation of high-risk behaviors.

Three doses are administered at 0, 1-2 months and 4-6 months. Because of the potential difficulties of patients returning for the second and third doses, it is important to consider that lapses in immunization do not require reinstitution of the entire series. Effective antibody responses are still induced by intervals of up to one year between the first and third doses. Because published studies have demonstrated the potential for low compliance for return for the second and third doses, clinicians may alternatively elect to use the newly approved two-dose schedule. Recombivax HB (Merck) is approved as a two-dose schedule for adolescents ages 11-15. The adult dose of Recombivax HB (10 µg) is given, with the second dose at 4-6 months. Decline in antibody titers has been shown to be similar to the three-dose schedule for up to two years. Published data have additionally shown that immunologic memory with the two-dose series to be similar to the three-dose series. Lapses in the two-dose series do not require reinstitution of the entire series. In children and adolescents in whom the series was begun with a 5-µg dose, the three-dose series should be completed.

Varicella

Despite its efficacy, use of varicella vaccine continues to be less than optimal. Adverse outcomes from varicella disease, including death, increase at age 15 years and older. Adolescents should be screened at age 11-12 years for varicella immunization or a reliable history of chickenpox. If immunization is needed, one dose should be administered to children younger than 13. Children 13 and older should be given two doses, separated by four to eight weeks. Clinicians may elect to perform serologic testing in adolescents with a questionable history of previous disease. Those patients 18 years of age and older without a reliable history of varicella have a 70%-90% likelihood of adequate immunity. Serologic testing is not necessary, however, as immunization given to an adolescent who is immune is well-tolerated. Because the varicella vaccine is a live-attenuated viral vaccine, it should not be given to adolescent girls who are or may be pregnant.

MMR

A two-dose MMR immunization schedule for students in primary and secondary schools and universities was recommended in 1989. This recommendation was instituted because primary vaccine failure was blamed for measles outbreaks that occurred in the 1980s. The second measles dose is recommended at entry to either elementary school (age 4-6 years) or middle school (age 11-12 years), depending in part upon state requirements. Children born prior to 1985 (and possibly after 1985, depending upon state requirements) may not have received the second dose; thus, assessment at the 11-12 year visit allows for identification of measles immunization deficiencies. Prior to administering MMR to adolescent girls, it is important to consider that the vaccine is live-attenuated, and thus screening for pregnancy (or the potential) is important.

Tetanus and diphtheria toxoids

Diphtheria resurgence in recent years in new countries of the former Soviet Union and in Europe dictates the importance of maintaining diphtheria immunity in the U.S. population. Studies have shown that booster immunizations for tetanus are essential for long-lasting immunity. The CDC has assessed that lowering the age for receipt of the first Td booster from 14-16 years of age to 11-12 years of age should increase compliance and maintain adequate immunity against diphtheria and tetanus. The immunization schedule recommends this booster at age 11-12 years if at least five years has elapsed since the previous tetanus and Td-containing vaccine (the fifth dose of the diphtheria-tetanus-acellular pertussis [DTaP] series is normally given at age 4-6 years).

Even if other immunizations are current for a child of 11-12 years of age, scheduling a clinic visit for administration of a Td booster at this age provides reason for a routine visit, and for provision of other age-appropriate health maintenance services. Beyond this age, Td boosters should be administered every 10 years. Booster immunizations should be given earlier if a tetanus-prone injury occurs, and if more than five years have passed since administration of the previous booster.

However, it is important to consider the current U.S. shortage (see special report).

The CDC has published temporary recommendations for priority indications for Td. Routine boosters for adolescents be deferred until a more ample supply of Td is available.

Additional immunizations

Adolescents should be assessed for additional immunizations based on risk factors. Adolescents at increased risk for pneumococcal disease should receive the 23-valent pneumococcal vaccine. This includes those who have anatomic or functional asplenia (including sickle-cell disease), nephrotic syndrome or chronic renal failure, cerebrospinal fluid leaks or immunosuppressive disorders (including HIV).

Adolescents who are at high risk of severe pneumococcal infection should be reimmunized once, at five or more years after initial immunization. This includes anatomic or functional asplenia (including sickle-cell disease), nephrotic syndrome or chronic renal failure, HIV infection, Hodgkin’s disease, lymphoma, leukemia or other immunosuppressive disorders. Mild adverse events (erythema, injection site pain) are relatively common with the pneumococcal vaccine.

Immunization against hepatitis A (HepA) may also be indicated for some adolescent living in states (or counties or communities) where rates of hepatitis A are at least twice the national average (see references). Adolescents traveling to or working in countries with intermediate to high endemicity, males who have sex with other males, illegal drug users, adolescents with clotting factor disorders (and who receive clotting-factor concentrates) or adolescents with chronic liver disease.

Adolescents who should be offered influenza vaccine include those who have chronic cardiovascular or pulmonary disorders (including asthma); reside in chronic-care facilities; have chronic metabolic disorders (including diabetes mellitus); have other chronic disorders, such as renal dysfunction, hemoglobinopathies or immunosuppressive conditions; receive long-term aspirin therapy; or have close contact with people at increased risk for complications of influenza (including people 65 or older).

Vaccines for college students

Although not included in the 2002 Immunization Schedule, immunization against meningococcal disease may be an important consideration for older adolescents entering college.

Guidelines for vaccine administration against meningococcal disease for college students were published by the CDC in 2000. College freshmen (specifically those living in dormitories) are at moderately increased risk of meningococcal disease. Because the overall risk of meningococcal disease among college students is low, and because vaccination of all college freshman living in dormitories is unlikely to be cost-effective, the CDC guidelines do not routinely recommend immunization of all such freshman. It is recommended that clinicians discuss the potential risks of meningococcal disease and benefits of immunization with adolescents (and their parents) planning on entering university life.

Unknown vaccination status

Adolescents without an immunization record can be assessed by assuming that vaccinations required by law have been given. This may not include, however, immunizations not given because of religious, philosophic or medical reasons. Those vaccinations not governed by law or regulation should be given and may be given simultaneously. Although such administration may require multiple vaccinations, simultaneous administration reduces the need for additional visits. Immunization with MMR and varicella should be separated by four weeks if not given simultaneously.

For more information:

• CDC. Immunization of adolescents: recommendations of the Advisory Committee on Immunization Practices. MMWR. 1996;45(RR-13):1-16.
• CDC. Prevention of hepatitis A through active or passive immunization: recommendations of the Advisory Committee on Immunization Practices. MMWR. 1999;48(RR-12):1-37.
• CDC. Alternative two-dose hepatitis B vaccination schedule for adolescents aged 11-15 years. MMWR. 2000;49:261.
• CDC. Meningococcal disease and college students. MMWR. 2000;49(RR-7):11-20.
• Wong VK. Compliance of hepatitis B vaccination in patients presenting to a teenage clinic. Pediatr Infect Dis J. 1994;13:936-937.
• Poland GA. Adolescent hepatitis B immunization: making it simpler. Pediatrics. 2001;107:771-772.
• Cassidy WM. A randomized trial of alternative two- and three-dose hepatitis B vaccination regimens in adolescents: antibody responses, safety and immunologic memory. Pediatrics. 2001;107:626-631.
• Schaffer SJ. The coming of age of adolescent immunization. Pediatr Ann. 2001;30:342-345.
• Further information on prioritization of administering existing supplies of Td can be found on the CDC Web site.