Human Papillomavirus (HPV) Vaccination
The management of cancer is almost always discussed within the context of the development of a cure once the diagnosis has been made. The notion that a vaccine could drastically reduce a person’s chances of developing certain types of cancer seemed fantastical in the past but became a reality in 2006 with the Food and Drug Administration’s (FDA) approval of the first vaccine against human papillomavirus (HPV), Gardasil®, followed by the approval of Cervarix® in 2009. Gardasil® 9 was approved by the FDA in December 2014 and this form of the vaccine protects against five additional HPV types.
With the approval of these vaccines, however, came significant and arguably unexpected skepticism and controversy about the utility and safety of their use that has had a durable impact on the HPV vaccination rates in the United States. Parents of young girls must grapple with the decision whether or not to have their daughters vaccinated against this virus.
Why has there been controversy over such a seemingly positive medical advancement that can potentially prevent millions of women (and men) suffering and possibly dying from cancer? The reasons are numerous and span the medical, social, political and even religious spheres. To obtain the full benefit of vaccination and prevent the HPV-related diseases for which the vaccine is approved, it must be administered before sexual activity is initiated, and this lower age limit is 9 years in both girls and boys for Gardasil®, and for girls in Cervarix®. The association of the HPV vaccine with an infection that is acquired through sexual activity has politicized its distribution and adoption by many parents, who balk at the idea of their daughters receiving this vaccine before their 10th birthday. Others bear a mistrust of the pharmaceutical industry and believe that the vaccine manufacturers are interested only in profit and not in advancing the health of children.
Few infectious diseases are as prevalent in human beings as HPV. Genital HPV is the most common sexually transmitted infection in the United States, with approximately 79 million people infected with the virus and 14 million new cases diagnosed each year. While the majority of HPV infections are asymptomatic and self-limited, persistent infection can have serious consequences. The array of disease conditions caused by HPV ranges from the arguably bothersome but ultimately benign (e.g., skin warts) to the potentially lethal (e.g., cervical, vaginal and vulvar cancer in women, penile cancer in men, and anal and oropharyngeal cancer in both genders) .
The HPV types that have a low risk for causing cervical cancer (e.g., types 6 and 11) can cause low-grade cervical changes and over 90% of genital warts. The high-risk HPV types (e.g., types 16 and 18) can lead to low- and high-grade cervical cell changes that precede the development of cancer and can also lead to overt malignancy. Cervarix® protects against types 16 and 18 and is approved for use only in females aged 9 to 26, while Gardasil® protects against types 6, 11, 16 and 18 and is indicated for use in both females and males aged 9 to 26 years.
People who oppose or are wary of HPV vaccination sometimes cite the adverse events that have been noted in the initial clinical studies of the vaccines. In general, the vaccines are very safe, with few serious side effects occurring in subjects who received them. The package insert for Gardasil® indicates that the most common adverse events seen in the clinical trials occurred in a small percentage of subjects and included headache, fever, nausea, syncope (fainting) and dizziness, and injection site reactions such as pain and redness. The adverse events seen with Cervarix® were similar.
Concerns have been raised by parents and others that HPV vaccination could lead to a perception by adolescents and young adults who receive it that they are at a lower risk of acquiring the disease, thereby increasing the likelihood that they engage in risky sexual behaviors and acquire sexually transmitted infections. Studies have not borne out these concerns, and there is a growing literature suggesting that HPV vaccination is unlikely to change sexual risk behaviors in young women. In both the sexually inexperienced and experienced subjects in one study (2), there was no correlation between the risk perception immediately after vaccination and sexual risk behaviors over the following six months. There are multiple factors that play a part in the decision by adolescents to engage in sexual intercourse or use condoms, including attitudes and beliefs, family structure, peer relationships, and exposure to the media. It could be that beliefs about reduced risk after HPV vaccination may not be significant enough a factor to influence sexual behaviors.
One issue that impedes the adequate coverage of adolescents with the HPV vaccine is adherence. The vaccine series comprises three separate doses, with one given at baseline, another one to two months after the first dose, and the last at 6 months. Adherence to the complete series may be challenging for some adolescents. The duration and strength of the protection afforded by the HPV vaccine in the setting of an incomplete or delayed course is unknown. One study in over 3,000 subjects (3) showed that over 50% of the second and third vaccination doses were received later than recommended, and the series completion rates were poor at 14% after six months and 26% after 12 months; similar findings have been reported elsewhere (4).
Given the relatively low vaccination rates that have been seen since the HPV vaccine was first approved for use, the concerns about the vaccine must be taken seriously by health care professionals in order to provide the best possible care for their female (and male) adolescent patients. Prevention of the sequelae of HPV infection, however, which can be debilitating or even fatal, should be the goal of everyone involved in the care of a patient, regardless of how this goal is achieved.
Based upon the favorable safety profile of the HPV vaccine and the comprehensive evidence obtained from the growing body of research on this topic that points to a distinct protective health advantage for those who receive the HPV vaccine, both of my daughters and my son will receive the HPV vaccine as soon as they reach the earliest recommended age. As always, however, each parent should decide what the best course of action is for their own child.
Legal Disclaimer: This article is designed to provide general information related to pediatric care. The information presented in this article should not be construed as formal medical advice, nor is it intended to create a doctor-patient relationship. The content is intended solely for informational and not for treatment purposes.
This article is not a substitution for professional medical diagnosis or treatment.
Dr. Tafadzwa Kasambira is a pediatrician who received his undergraduate training at McGill University in Canada and graduated in 2002 from Tufts University School of Medicine, where he also completed a degree in public health. He completed his pediatric residency training at Harvard University in 2005 and completed a fellowship in infectious diseases at Johns Hopkins University in 2008. He has been a medical officer at the FDA for the last six years. He and his husband are the proud fathers of three children.