Adolescent Immunization Backgrounder

Adolescent Immunization Backgrounder
The US immunization program vaccination schedule is a blueprint that provides individuals with continued immunity throughout their lives. US immunization rates are highest in infants and toddlers, lower in adolescents, and lowest in adults. Data from the Centers for Disease Control and Prevention (CDC) show that recommended vaccines are underused in adolescents. Vaccines for adolescents are especially critical as they protect against serious and deadly diseases including a wide range of cancers and a particularly severe type of meningitis. In addition to disease prevention, focusing on vaccinating adolescents encourages a lifelong commitment to better preventive healthcare through immunization. 

Recommended Vaccinations 
Three vaccines are currently recommended for first-time administration at age 11-12 years. They are the quadrivalent meningococcal conjugate (MCV4); tetanus, diphtheria, and pertussis (Tdap) booster; and human papillomavirus (HPV). For MCV4, a booster is also recommended at age 16 years. Influenza vaccination is recommended annually for everyone age six months and older, including adolescents. “Catch-up” vaccines, for adolescents who were not immunized or were underimmunized as infants and toddlers, are hepatitis B; polio; measles, mumps, and rubella (MMR); and varicella (chickenpox). Finally, three vaccines are recommended for adolescents with certain risk factors: hepatitis A, pneumococcal, and meningococcal B, which protects against the B strain of meningococcal bacteria. 

The CDC, American Academy of Pediatrics, American Academy of Family Physicians, American Medical Association, and Society for Adolescent Health and Medicine all recommend a routine healthcare visit that includes vaccination at age 11-12 years. Adolescents who are not vaccinated at this age should have their vaccines brought up-to-date as soon as possible.

Vaccines Protect against Serious and Deadly Diseases 

Mengingococcal disease
Anyone can get meningococcal disease, but adolescents have an increased risk of getting the disease. Even with rapid, appropriate treatment, approximately 10 percent of those who become infected will die, and up to 20 percent of survivors will suffer serious and permanent complications including brain damage, hearing loss, and amputations. 

The most common clinical presentations of meningococcal disease are meningitis and meningococcal bacteremia; each can occur alone or in combination with the other. Meningococcal disease is marked by frequently nonspecific symptoms at onset and very rapid progression that can kill an otherwise healthy adolescent in less than 48 hours. 

Vaccination with a quadrivalent vaccine that protects against four major meningococcal serogroups (A, C, W, and Y) is recommended for all adolescents at age 11-12 years with a booster dose at age 16 years. Two newer vaccines were recently approved in the US to protect against serogroup B, which is now the most common cause of meningococcal disease in US adolescents. CDC has made limited recommendations for their use and is considering additional recommendations. Serogroup B vaccines are currently recommended for individuals at increased risk of infection, including college students on campuses experiencing outbreaks caused by the serogroup B bacteria.

Human papillomavirus virus
HPV causes virtually all US cases of cervical cancer and about 91 percent of anal cancers, 75 percent of vaginal cancers, 69 percent of vulvar cancers, and 63 percent of penile cancers. HPV16, specifically, has also been identified as a major cause of oropharyngeal cancers, including cancers in the throat, at the base of the tongue, and in the tonsils. The number of HPV-related oropharyngeal cancers in the US is expected to surpass HPV-related cervical cancers by 2020.

HPV vaccination is currently recommended for all adolescents (male and female) at age 11-12 years as a three-dose series over six months. It is recommended for all females through age 26 years and males through age 21 years, who did not get any or all of the recommended vaccine doses when they were younger. The vaccine is also recommended for all males who have sex with males and males with compromised immune systems (including HIV) through age 26 years, if they were not fully vaccinated when they were younger.

There are currently three vaccines available to prevent HPV infection: a 9-valent vaccine (9vHPV), a quadrivalent vaccine (4vHPV), and a bivalent vaccine (2vHPV). 9vHPV and 4vHPV are approved for use in both males and females; 2vHPV is approved for use only in females. HPV vaccination does not eliminate the need for cervical cancer screening, because the vaccines do not protect against every HPV strain that can cause cervical cancer.

Pertussis, tetanus, and diphtheria  
Although most infants and toddlers are vaccinated against pertussis, immunity wanes after about 5 to 10 years, so by the time they reach adolescence, these vaccinated children can get whooping cough. The illness is usually milder (they may never know they had it), but adolescents are common transmitters of the infection to infants, who are at the highest risk of death. In recent years, the US has experienced the highest number of pertussis cases since 1959. In 2012, outbreaks were reported in a majority of states with more than 32,000 cases and 16 deaths, most of which were in infants. This is why a booster vaccination at age 11-12 years is important, and also why pregnant women need to get Tdap vaccination in the third trimester of every pregnancy. Tdap protects pregnant women, their developing babies, and eventually their newborns.

Diphtheria is rare in the US, however, it still exists in other countries and can pose a serious threat to any individual not fully immunized who travels abroad or who has contact with infected foreigners in the US. 

The bacteria that cause tetanus are everywhere, living in dirt and soil all around us, but cases are rare because of widespread immunization. Although it is rare, tetanus is deadly, killing one in 10 individuals who get it. 

The tetanus, diphtheria, and pertussis booster replaces the previously recommended tetanus and diphtheria (Td) booster at age 11-12 years or in older adolescents who need a Td booster. The vaccine is also recommended in place of one Td booster for adults who have not previously received Tdap. CDC recommends Tdap vaccination for pregnant women in the third trimester of each pregnancy.

Influenza 
Influenza and its complications are responsible for 3,000-49,000 US deaths each year, depending on the severity of the circulating viruses. CDC recommends annual influenza vaccination for everyone age six months and older. 

While influenza is generally more severe in the very young and older persons, adolescents, even healthy ones, can suffer extreme consequences and even death (though rare). School-age children also have the highest influenza attack rates.

Hepatitis B
Widespread infant immunization began in the US in 1991 and resulted in a dramatic reduction in US hepatitis B incidence. Today, the majority of new hepatitis B infections in the US occur in young adults. An estimated 700,000 to 1.4 million individuals have chronic hepatitis B infection. Chronic infection can lead to cirrhosis, liver cancer, and death.  

Hepatitis B vaccination is recommended for all adolescents younger than age 19 years who were not previously vaccinated with a full three- or four-dose series.

Polio
In the early 1950s, more than 20,000 cases of polio occurred each year. After routine vaccination began in 1955, the number of cases dropped to about 3,000 by 1960; by 1979, there were only about 10 cases annually. While no polio has been reported in the US for over 20 years, the virus continues to circulate globally and importation and outbreaks are a possibility if high vaccination rates are not maintained. Any adolescent not fully vaccinated against polio should complete the recommended vaccine series.

Measles, mumps, and rubella (MMR)
In 2014, the US experienced the greatest number of measles cases since the disease was eliminated in the US in 2000. Since January 2015, the US has been experiencing a multi-state measles outbreak linked to a California amusement park. The outbreak likely started from a traveler who became infected with measles overseas, but it proliferated because of gaps in US herd immunity attributed to pockets of lower measles vaccination coverage. By early April 2015, 147 cases in seven states were linked to the outbreak. Additional cases occurred in many more states (18 states in total) that were not connected to the outbreak.
 
Like measles, widespread transmission of mumps and rubella (German measles) have been eliminated. The number of US mumps cases ranges from a few hundred to a few thousand each year, but there have been some small outbreaks on college campuses, and two larger outbreaks among school-aged children: one in an insular religious community in New York City and the other among children in the US Territory of Guam.

Any adolescent not fully vaccinated against measles, mumps, or rubella should be immunized using the MMR vaccine.

Varicella
The risk of complications from varicella (chickenpox) varies with age. Among children age one to 14 years, the fatality rate from varicella is approximately 1 per 100,000 cases. Among young people age 15 to 19 years, it is 2.7 per 100,000 cases. Catch-up vaccination during adolescence will continue to provide protection against varicella during adulthood.

Hepatitis A
Since 1996, and particularly since a 1999 recommendation for routine hepatitis A vaccination of children living in areas with consistently elevated hepatitis A rates, national hepatitis A rates have declined sharply. Hepatitis A causes nausea, anorexia, fever, malaise, abdominal pain, and jaundice.

Vaccination is recommended for adolescents who live in states or communities that historically have higher rates of hepatitis A cases; are men who have sex with men; use illegal injection or non-injection drugs; have an occupational risk for exposure to hepatitis A; have chronic liver disease or clotting factor disorders; or who are in close contact with adopted children newly arriving from countries where hepatitis A is common.

Pneumococcal disease
Although the incidence of pneumococcal disease among adolescents is the lowest of any age group, about 6.8 million children and adolescents age two to 18 years have chronic illnesses―such as diabetes or heart, lung, liver, or kidney disorders―that place them at high risk for pneumococcal disease and its complications. For these reasons it is important to have this population vaccinated. Two vaccines are used in the US for pneumococcal disease immunization: a 13-valent conjugate vaccine (PCV13) and a 23-valent polysaccharide vaccine (PPSV23). Details on use of these vaccines in adolescents are available on the CDC childhood immunization schedule.

Selected References
CDC. Vaccine Information Statements.
www.cdc.gov/vaccines/hcp/vis/index.html

CDC. Advisory Committee on Immunization Practices (ACIP). www.cdc.gov/vaccines/acip/index.html.

NFID. Addressing the challenges of serogroup B meningococcal disease outbreaks on campuses: a report by the National Foundation for Infectious Diseases. adolescentvaccination.org/resources/meningococcal-b-report.pdf. May 2014.

NFID. Call to action: HPV vaccination as a public health priority. adolescentvaccination.org/professional-resources/hpv-resource-center/hpv-call-to-action.pdf. August 2014.

NFID. The case for improving adolescent health: helping prepare adolescents for a healthy future. adolescentvaccination.org/resources/case-for-improving-adolescent-health.pdf.


March 2015