What is the human papillomavirus (HPV)?
The human papillomavirus (HPV) is an infection that is one of the causes of cancer. HPV leads to the development of malignant tumors in the cervix, vulva, vagina, anal, oropharynx, and penis. This virus is transmitted through sexual contact. There are several genotypes ("types") of HPV, each of which affects the body's cells to varying degrees. For instance, according to research, types 16 and 18 are responsible for 70% of cervical cancer cases, while types 31, 33, 45, 52, and 58 account for 20% of cases.
Reasons to get HPV vaccine
Vaccination reduces the risk of HPV infection and, consequently, the likelihood of subsequent oncogenic effects leading to cancer development. This is why headlines like "Cancer Vaccine" are entirely justified. However, it's important to note that these vaccines do not "cure" existing infections; they cannot eliminate the virus once a person is already infected.
One study showed that vaccinating the entire population of 12-year-old girls in the United States annually would prevent over 200,000 cases of HPV infection and save 3,300 women from cervical cancer, assuming screening continues according to current recommendations.
Should men also get vaccinated?
HPV is transmitted through sexual contact and can lead to cancer in organs beyond the female reproductive system. HPV can cause cancer of the anal, penis, and oropharynx. Types 16 and 18 of HPV are responsible for anal cancer in 90% of cases. Vaccination helps reduce the spread of HPV, thus protecting not only yourself but also your sexual partner.
At what age should vaccination be considered?
The peak of HPV infection occurs between the ages of 16 and 25, during the active period of sexual activity. The Advisory Committee on Immunization Practices (ACIP) considers the "optimal age" for vaccination to be 11-12 years old (though vaccination is generally allowed from the age of 9). There was once a misconception that vaccination is ineffective after the onset of sexual activity, but this is incorrect. With an increasing number of sexual partners, the risk of infection with different types of the virus rises, leading to a greater likelihood of developing malignant tumors. The medical community recommends vaccination for everyone up to the age of 26. For those aged 27 and older, it's recommended to discuss vaccination with a gynecologist to jointly decide on the necessity and effectiveness of the prevention strategy. The upper age limit for vaccine application is 45 years. Research suggests that vaccination generates fewer antibodies in response at older ages. While vaccination might still be beneficial for some individuals over 45, this matter is not yet well-studied. Medical scientific communities believe that, given the limited quantity and cost of the vaccine, vaccinating individuals over 45 is a fewer effective means of preventing oncological diseases, both from a public health and an economic perspective.
What vaccines are available and what types of HPV do they target?
Currently, there are three vaccines worldwide with proven clinical efficacy:
- Gardasil 4 targets HPV types 6, 11, 16, and 18
- Gardasil 9 targets HPV types 6, 11, 16, 18, 31, 33, 45, 52, and 58
- Cervarix targets HPV types 16 and 18
When there's a choice, Gardasil 9 is generally favored since it protects against a greater number of HPV types.
How many doses are administered as part of the vaccination course?
The vaccination schedule depends on the age, according to recommendations from the Centers for Disease Control and Prevention (CDC):
- If vaccination is done between ages 9-14: 2 doses
- If vaccination is done at age 15 or older: 3 doses
However, in 2022, the World Health Organization (WHO) updated their vaccination schedule recommendations and published their position as follows:
- If vaccination is done between ages 9-14: 1 or 2 doses
- If vaccination is done between ages 15-20: 1 or 2 doses
- If vaccination is done at age 20 or older: 2 doses
These changes in the vaccination schedule are supported by research, which suggests that single-dose vaccination, referred to as the alternative schedule, can provide effectiveness and long-term protection comparable to a two-dose regimen.
Due to cost and limited vaccine availability, it may sometimes be possible to receive only 1 or 2 doses. Of course, it's better to follow the recommended vaccination schedule to establish protective immunity, but still, receiving even one dose is better than having no protection at all.