Infection with the human papillomavirus (HPV) is the primary factor causing cervical intraepithelial neoplasia (CIN). Other microorganisms found in CIN cases, such as herpes simplex virus type 2 or Chlamydia trachomatis, may influence the natural course of HPV infection, including its prolonged persistence or progression to CIN.
HPV infections cause cervical cancer but are also largely responsible for anal, vulvar, and vaginal cancers, and are associated with about 30% of penile cancers and approximately 70% of head and neck cancers. They also cause benign genital warts.
HPV infection is the most common sexually transmitted infection, estimated to affect about 80% of women and men mainly before the age of 45, and it occurs transiently in about 50% of sexually active individuals.
About 40 types of HPV (out of more than 100 types) cause infections of the genital mucosa and oral cavity.
Low-risk types – HPV 6 and 11 cause genital warts and recurrent respiratory papillomatosis.
High-risk types – HPV 16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59, 68, 73, 82 contribute to the development of cancers.
The high infectivity of the HPV virus leads to a 40-60% chance of infection during a single sexual encounter.
The body’s immune system usually fights off HPV infection, which typically resolves within 24-36 months. If the infection persists, it leads to the progression of cellular changes, known as dysplasia phases, and after several years to the development of invasive cancer.
HPV types 16 and 18 are most frequently found in neoplastic changes of the cervix, vulva, vagina, anus, and penis. Meanwhile, viruses with low oncogenic potential – types HPV 6 and 11 are responsible for 90% of cases of genital warts or so-called condyloma acuminata, as well as papillomatous changes in the oral cavity, throat, and larynx.
Vaccines used for HPV infection prevention do not contain viral DNA and are safe for the vaccinated individual.
Recommendations and guidelines for the use of the HPV vaccine (developed by: Advisory Committee on Immunization Practices at the Centers for Disease Control)
HPV Vaccines
Bivalent (HPV 16,18), quadrivalent (HPV 6,11,16,18), and nonavalent (HPV 6,11,16,18,31,33,45,52,58) vaccines are available for use in women, while the quadrivalent and nonavalent can also be administered to men.
Age
Routine vaccinations for girls should be performed at ages 11-12 years: the vaccination series can begin from the ninth year of life, but also later, up to ages 13-26 years. If possible, vaccination should be done before the onset of sexual activity and potential exposure to HPV, but girls and women after potential HPV contact should also be vaccinated.
HPV Vaccination for Men
Routine vaccination of boys is recommended at ages 11-12 years. Vaccinations can be applied from the ninth to the 21st year of life. Men with compromised immunity may be vaccinated up to the age of 26.
Method of Administration
Vaccines are administered intramuscularly, preferably in the deltoid muscle.
Vaccination Schedule
All three vaccines are administered in three doses. The second dose is given 1-2 months after the first, and the third dose 6 months after the first dose.
The minimum interval between the first and second doses is 4 weeks, while between the second and third doses it is 12 weeks.
Incorrect doses or doses administered at shorter intervals should be repeated.
Interruption of the HPV Vaccination Cycle
The vaccination series does not need to be restarted from the beginning. The second dose should be applied as soon as possible and the third after a minimum of 12 weeks. If there is a delay concerning the third dose, it should be administered as soon as possible using the same or a different HPV vaccine than previously used.
Simultaneous Administration with Other Vaccines
HPV vaccinations can be given with other vaccines, such as against tetanus, diphtheria, and pertussis or the quadrivalent against meningococcus, on the same day but in different parts of the body.
Vaccination in Individuals with Ambiguous or Abnormal Cytological Smear Results or HPV Infection
The vaccine does not have a therapeutic effect on existing HPV infections or changes in the cervix. However, it can protect against infection with other types of HPV and protect against reinfection after treatment.
No prior testing for HPV DNA or antibodies against HPV is required before vaccination.
Breastfeeding
Breastfeeding women can be vaccinated against HPV.
Pregnancy
Vaccination during pregnancy is not recommended due to insufficient safety data. If a woman is pregnant after starting the vaccination series, the remaining doses should be administered after the pregnancy.
Vaccination of Individuals with Compromised Immunity
HPV vaccines are non-infectious and can be administered to individuals with weakened immunity due to diseases or medications. The effectiveness of the vaccine may be lower than in individuals with normal immune function.
Screening for Cervical Cancer in Vaccinated Women
Screening guidelines for cervical cancer in vaccinated women do not change.
To expand the scope of immunization, individuals vaccinated with the 2- and 4-valent vaccine can receive the 9-valent vaccine.
Girls under 15 years of age who have been vaccinated with at least 2 doses of the 2- or 4-valent vaccine can be revaccinated with two doses of the 9-valent vaccine spaced 6 months apart; after 15 years of age, revaccination requires the full three-dose cycle (publication Van Damme. “Vaccine 2016”)
Observations to date confirm slightly greater protection of the 9-valent vaccine in preventing dysplastic changes, especially of higher degrees, but no vaccine provides complete efficacy.
Vaccinations significantly reduce the risk of changes caused by HPV infection but do not completely eliminate them. Women who have been vaccinated should still undergo routine preventive screenings.