On July 25th, the CDC released data from the 2012 National Immunization Survey-Teen in a Morbidity and Mortality Weekly Report that show no improvement in the coverage rate for HPV vaccine for girls during the prior year. HPV vaccine coverage for one or more doses of HPV vaccine was only 53.8% in girls aged 13 to 17 years, and vaccine coverage for three or more doses of HPV vaccine was 33.4%.
Worse than that is the percentage (84%) of HPV-unvaccinated girls who had missed an opportunity to be immunized, which was defined by the CDC as a health care encounter occurring on or after a girl’s 11th birthday, during which at least one vaccine was received, but HPV vaccine was not given. The data from 2012 on the uptake of the other vaccines recommended for this age group are not yet available; however, in the past few years, the uptake of HPV vaccine in girls has lagged behind the other two vaccines given to adolescents aged 11 to 12 years.
Coverage in the 2011 survey for tetanus-diphtheria-acellular pertussis vaccine and meningococcal conjugate vaccine (MCV4) were at 78.2% and 70.5%, respectively. The data on coverage of HPV vaccine in boys are not yet published.
Failure to meet goals
These very disappointing findings indicate we are far below the goals set by the CDC, the American Academy of Pediatrics and the American Academy of Family Physicians for universal immunization of this age group against HPV. The result is that a large number of patients remain unprotected against an important cancer-causing virus. And, these data come at a time when we are beginning to see significant evidence from the United States and other countries of the effectiveness of the currently licensed HPV vaccines.
These findings appear to be the result of a number of factors we as providers can effectively address. They include parental lack of knowledge of HPV and its consequences, the belief that their child does not need the vaccine or is not sexually active, a concern that giving the vaccine may result in an increased likelihood that the child will become sexually active and concerns about vaccine safety. Some parents report that their child’s physician did not recommend HPV vaccine or that their physician provider did not give a strong recommendation, thus, in effect, making it acceptable to delay administration.
Also troubling is that some parents indicate that they would have considered giving HPV vaccine to their child if their physician had made them aware of the vaccine and recommended it at that health visit. In all studies of the decision to vaccinate, parents indicate that the most important influence on their decision is a recommendation by their physician, who for most parents is their most trusted source of vaccine information.
HPV disease burden
HPV is the most common sexually transmitted infection in the United States. The highest prevalence is in sexually active adolescents and young adults. Infection occurs soon after the initiation of sexual activity. In the 2006-2008 National Survey of Family Growth, 21% of boys and 23% of girls aged 15 years reported having had virginal sex; and by age 18 years, the numbers increased to 59% and 56%, respectively. Recent studies indicate that non–intercourse-related sexual contact may also result in transmission of HPV. The lifetime risk for acquiring HPV is 80%.
Although most HPV infections are silent and resolve within 2 years, persistent infection with an oncogenic serotype of HPV can lead to cancer. HPV causes virtually all cases of cervical cancer and a significant percentage of cases of other anogenital and oropharyngeal cancers in females and males.
An estimated 26,000 HPV-related cancers, more than 17,000 in women and more than 8,000 in men, are diagnosed in the United States each year. Despite cervical screening protocols, more than 11,000 women are diagnosed with cervical cancer each year in the United States and 4,000 will die. Anal cancer rates are increasing in both men and women at a rate of 4.5% a year and oropharyngeal cancer rates in men are increasing as well. HPV types 16 and 18, which are in both licensed HPV vaccines, are responsible for more than 70% of cervical cancers and approximately 80% of all HPV-associated cancers. Most oropharyngeal cancer due to HPV is caused by HPV type 16.
HPV vaccines prevent cancer
Both of the licensed HPV vaccines are designed to prevent cancer by providing protection against HPV types 16 and 18. The quadrivalent vaccine also targets genital warts by including types 6 and 11. In clinical trials, both vaccines were found to be highly efficacious in preventing infection and cancer precursor lesions. The recommendation from the Advisory Committee on Immunization Practices and AAP for giving HPV vaccine to all 11- to 12-year-olds is based on the available data concerning safety and efficacy, and the epidemiology of HPV infection. Modeling indicates that the greatest benefit of HPV vaccine would be achieved if vaccine is given before the onset of sexual activity. Antibody titers post-immunization are highest in this age group. The safety of both HPV vaccines has been clearly demonstrated. More than 50 million doses of quadrivalent HPV vaccine have been distributed in the United States since licensure. Post-licensure monitoring of reports to the Vaccine Adverse Event Reporting System (VAERS) and prospective phase 4 studies have not demonstrated any safety signal or raised any safety concern.
HPV vaccine effectiveness
In June, the CDC published evidence of the rapid impact of HPV vaccines on the prevalence of HPV types 6, 11, 16 and 18. As part of the National Health and Nutrition Examination Survey, a cross-sectional study conducted annually by the CDC, a self-collected cervicovaginal swab was tested for HPV serotypes. Among 14- to 19-year-old females, the prevalence of HPV types 6, 11, 16, and 18 decreased from 11.5% in 2003-2006, the years just before introduction of the quadrivalent vaccine, to 5.1% in 2007-2010. This 56% reduction in prevalence was even greater than expected due to the poor rate of uptake, indicating a high degree of effectiveness and possible protection of unvaccinated population through herd immunity.
Other countries are also reporting a rapid impact after vaccine introduction. In Australia, where approximately 83% of 12- to 17-year-old girls and 55% of women aged 18 to 26 years received at least one dose of quadrivalent HPV vaccine, there has been a marked reduction in cases of genital warts and a decrease in HPV 16/18 genotype recovery from cervical specimens.
Challenges and role of the provider
Adolescent immunization presents unique challenges. Adolescents are more likely to visit the office with an acute illness or injury rather than for routine preventive care. Every office visit should be used as an opportunity to review immunization status and update any patient who is behind schedule. The return visits required for completion of a three-dose immunization series are an additional challenge. Recent articles indicate that the recall and reminder protocols that improve immunization rates in young children also may be helpful for adolescents, as well as including the new social media adolescents frequently use.
We as providers can markedly influence the uptake of HPV vaccine. HPV vaccines give us a remarkable opportunity to protect our patients against another viral cause of cancer. As with hepatitis B vaccine, HPV vaccine must be given before exposure to be effective. Since the time of exposure cannot be predicted during adolescence, it is imperative that we educate parents on the importance of providing this vaccine to 11-to-12-year-old girls and boys. It is our responsibility to take the time to educate parents about the long-term consequences associated with HPV infection, correct misperceptions about HPV vaccine safety, make parents aware of the data that HPV vaccination in the recommended ages is not associated with increased sexual activity, and make as strong a recommendation for giving HPV vaccine as we do for Tdap and MCV4.
The CDC has numerous resources available to providers and parents.
CDC. MMWR. 2013;62(29):591-595.
Markowitz LE. J Infect Dis. 2013;208:385-393.
For more information:
Joseph A. Bocchini Jr., MD, FAAP, is professor and chairman of the department of pediatrics at the Louisiana State University Health Sciences Center in Shreveport, La. Bocchini is a member of the ACIP.
Disclosure: Bocchini reports no relevant financial disclosures.