HPV Vaccination: A Sexual Health Harm Reduction Success Story
While curing cancer would revolutionize healthcare, preventing it is just as important—and for some cancers, more accessible and realistic. Sunscreen, a widely accepted harm reduction intervention, reduces the risk of skin cancer. While more invasive, preventive mastectomy for people with a genetic predisposition to breast cancer is another such intervention. There are also two vaccines that can decrease cancer risk: hepatitis B vaccination can prevent liver cancer, and human papilloma virus (HPV) vaccination can prevent cervical cancer, anal cancer, and some cancers of the head and neck. Recent research highlights the benefits of HPV vaccination and the need to continue promoting this highly effective, safe, and cost-effective harm reduction tool.
The first-generation HPV vaccine was introduced in 2006. Though originally recommended for females between the ages of 9 and 26, the current vaccine is now recommended for all people ages 9 to 26 (and approved for use up to age 45). Since HPV is an extremely common virus, the vaccine is most beneficial if given before a young person becomes sexually active—one reason the Centers for Disease Control and Prevention (CDC) recommend receiving the two-vaccine series between ages 11 and 12. The other is that the immune systems of people this age respond more strongly to the vaccination than those of older people.
Almost 20 years of data show significant declines in HPV infections among women in the United States. Recent evidence from Scotland highlights just how effective the vaccine is at preventing cervical cancer under real-world circumstances. Reviewing data from 447,955 individual records, the researchers found zero cases of invasive cervical cancer among women who received the full HPV vaccination course between ages 12 and 13. Although some may develop cervical cancer in the future, these results still suggest that the vaccine is stunningly effective.
Another study that assessed anal cancer occurrence among Danish women found similarly exceptional results: of the 374,489 who received at least one dose of the vaccine by age 17, fewer than five developed anal cancer. For comparison, 37 cases of anal cancer occurred among the 594,392 unvaccinated women—meaning the probability of vaccinated women getting anal cancer was 70 percent lower.
As of 2019, more than half of people ages 13 to 17 in the United States were fully vaccinated against HPV. A slightly higher percentage of females were fully vaccinated compared to males. Although individuals are best protected by receiving the vaccination themselves, there is some evidence that widespread vaccination has also decreased HPV rates in unvaccinated populations—suggesting the country may have achieved some level of herd immunity.
The original vaccine has been updated to protect against nine HPV strains as opposed to four. These strains are responsible for 80 to 90 percent of HPV-related cancers and about 90 percent of genital warts. Additionally, the dosing schedule has been simplified for younger people—in 2016, the recommended three-dose series decreased to a two-shot series for youth ages 11 and 12. Earlier this year, Merck, maker of the HPV vaccine, announced a clinical trial testing the efficacy and safety of a single dose compared to the three-dose series in people ages 16 to 26. The prospect of single-dose protection is exciting because a significant number of people who get the first dose do not complete the series. A single-dose protocol would alleviate the burden of returning to a medical provider for follow-up vaccines.
While vaccine safety concerns some people, the HPV vaccine has proven itself safe and well-tolerated. The most common side effects of HPV vaccination are pain, redness, or swelling at the injection site; fever; headache; fatigue; nausea; and muscle or joint pain, all of which usually resolve quickly. Over a three-year period, the CDC received 7,244 reports of adverse reactions out of about 28 million doses given; of these, only about 3 percent were considered serious. No unanticipated side effects were reported, and the patterns and quantity of reports was similar to other vaccines, such as those for tetanus and flu. On the other hand, the lifetime risk of cervical cancer is about 0.7 percent. Of people who get cervical cancer, 32.8 percent are not expected to survive five years or more.
Recent evidence confirming the high efficacy of HPV vaccination highlights exactly how preventable HPV-related cancers are. HPV vaccines are a sexual health success story that shows how harm reduction permeates many of the choices people make in an attempt to preserve their health.