HPV VACCINES
Overview
Persistent cervical infection with high-risk human papillomavirus (HPV) genotypes is necessary for the development of cervical cancer and its immediate precursor lesions, CIN3
HPV16 & 18 contributes to about 70% of cervical cancers
HPV 31, 33, 45, 52, 58 are responsible for 20% cervical cancers
90% HPV infections are transient, becoming undetectable within one to two years
Hpv Vaccines
- DNA free VLPs- empty capsids, non-infective, non-oncogenic
- Prophylactic Vaccines protect against acquisition of HPV infection and development of HPV associated disease
- Bivalent vaccine cover HPV 16, 18
- Quadrivalent vaccine cover HPV 6, 11, 16, 18
- Nonavalent vaccine cover HPV 6, 11, 16, 18, 31, 33, 45, 52, 58
- Therapeutic Vaccines induce regression of existing HPV associated lesions and are under development
Age at Initiation of Vaccination
- Advisory committee on immunization practices by United States recommends:
- Routine HPV Vaccination at 11-12 years, though it can be administered from 9 years onwards
- For those aged between 13 to 26 years, who have not been previously vaccinated, catch-up vaccination is recommended
- For adults 27 years or older, decision to vaccinate is made on individual basis. Likely benefit and cost-effectiveness is lower due to chances of prior exposure
- The optima timing is “Before the Sexual Debut”
Choice of Vaccine
- Any of the three vaccine types can be given depending upon availability. If cost and availability is not an issue then 9- valent vaccine is recommended. Serological or HPV DNA testing not warranted
- Ideally the same formulation should be used to complete the series, bit if previous formulation is unknown or unavailable, a different formulation can be given.
Dosing Schedule
- Initiation before 15 years of age- Two doses at 0 and at 6 to 12 months. If the second dose was administered less than five months after the first, the dose should be repeated.
- Initiation at age of 15 years or later- Three doses at 0, 1 to 2 and at 6 months. The minimum intervals between the first two doses is four weeks, between the second and third doses is 12 weeks, and between the first and third dose is five months.
- Immunocompromised patients- 3 doses, regardless of age
- Missed dose- vaccination series can be resumed without restarting the series.
- Not recommended during pregnancy, but if given inadvertently during pregnancy, one can continue it and complete the rest of doses after delivery
- Can be given during breast feeding
- Excellent antibody responses- seroconversion rates of 93 to 100 percent in females and 99 to 100 percent in males.
- vaccine is safe and well tolerated apart from mild injection site reactions and reports of post-vaccination syncopal events.
Post Vaccination Surveillance
- HPV immunization is not effective in clearing HPV infection, genital warts, or cervical intraepithelial neoplasia that is already present.
- HPV vaccine does not protect against 100 percent of types known to cause cervical cancer.
Thus, HPV vaccination status does not impact cervical cancer screening recommendations.