HPV Vaccines

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.

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