Behind the Numbers: HPV Vaccination Is Highly Effective

Lisa Schulmeister, RN, MN, APRN-BC, OCN®, FAAN

Editor-in-Chief OncLive Nursing

Oncology Nursing Consultant, Adjunct Assistant Professor of Nursing Louisiana State Health Sciences Center in New Orleans, Louisiana

According to the Centers for Disease Control and Prevention (CDC), 79 million Americans, most in their late teens and early 20s, are infected with the human papillomavirus (HPV). Each year, about 14 million people become newly infected.

HPV is known to cause oropharyngeal and anal cancers in both men and women, penile cancer in men, and cancers of the cervix, vulva, and vagina in women. In the United States each year, about 17,000 women and 9000 men develop HPV-related cancers. The death rate from cervical cancer is very low in the United States (3 per 100,000) because cervical cancer is usually curable when detected early. Unfortunately, there are no other routine screening tests for other types of HPV-related cancers. HPV vaccination is therefore integral to reducing the development of these cancers. Two vaccines (Cervarix and Gardasil) protect against cervical cancers in women. One vaccine (Gardasil) also protects against genital warts and cancers of the anus, vagina, and vulva. Both vaccines are available for females and only Gardasil is available for males.

HPV vaccination is highly effective. In large clinical trials, vaccination has been shown to significantly reduce the chance that women will develop the cervical, vaginal, and vulvar abnormalities that precede cancer. Similarly, it has been shown to reduce the rates of tissue abnormalities that precede anal cancer in men. Between 2007 and 2010, the prevalence of HPV types that the vaccine protects against fell by 56% compared with the 4-year period before the vaccines were available. This improvement is significant, considering that in 2010, only one-third of girls between the ages of 13 and 17 years had received the recommended three doses of the vaccine.

Despite its effectiveness, the question of HPV vaccine safety continues. Media reports of girls who are incapacitated, are now walking backward, or have sustained head injuries from falling after receiving the injection have raised concern about vaccination risks versus benefits. In October 2013, the Japanese government sent formal notifications to local health officials saying that HPV vaccines should not be administered until safety concerns are investigated. In Japan, the vaccine is supplied at no cost. As of December 2012, 8.29 million people had received the vaccine there, and as of March 2013, 1968 adverse events had been reported to the country’s Vaccine Adverse Reactions Review Committee, including 358 cases that were classified as serious. In Japan, girls will continue to be able to receive the HPV vaccination for free. However, healthcare providers must now inform the girls that the health ministry does not recommend it. In the United States, postlicensure vaccine safety monitoring is conducted by federal agencies and the vaccine manufacturers. From June 2006 to March 2013, the Vaccine Adverse Event Reporting System (VAERS) recorded that 57 million doses of HPV vaccines were distributed, and 22,000 adverse event reports occurring in girls and women who received HPV vaccines were submitted. Most (92%) were nonserious and included syncope, dizziness, nausea, headache, fever, hives, and local injection reactions.

In 2011, investigators using the Vaccine Safety Datalink (VDS) studied the occurrence of specific adverse events following more than 600,000 doses of Gardasil. Adverse events in the HPV-vaccinated population were compared to adverse events that occurred with other vaccines, and included Guillain—Barré syndrome, stroke, venous thromboembolism, appendicitis, syncope, and allergic reactions. None of these adverse events were found to be any more common after HPV vaccination than among the comparison groups.

HPV vaccination benefits outweigh its risks. It is also important for women to have regular Pap smears to detect cell abnormalities that can lead to cervical cancer. An Australian study found that some women are forgoing Pap testing because they have been vaccinated. While the vaccine protects against some of the HPV strains that cause cervical cancers, it does not protect against all of them, and regular Pap smears are essential in the early detection of cervical cancer.