What are the current recommendations for HPV vaccination (Gardasil 9) regarding age groups, dosing schedules, catch‑up vaccination, contraindications, pregnancy, and immunocompromised patients?

HPV Vaccination Guidelines

Routine Vaccination Age and Schedule

All children should receive HPV vaccination starting at age 11 or 12 years, though vaccination can begin as early as age 9 years, with the dosing schedule determined by age at initiation. 1, 2, 3

Two-Dose Schedule (Ages 9–14 Years)

• For individuals initiating vaccination before their 15th birthday, administer 2 doses with the second dose given 6 to 12 months after the first dose 1, 2, 3
• The minimum acceptable interval between doses is 12 weeks (3 months), though longer intervals closer to 12 months produce stronger immune responses 2, 4
• This schedule is based on robust immunogenicity data showing that younger adolescents (ages 9–14) mount significantly stronger antibody responses than older individuals receiving 3 doses 2, 5

Three-Dose Schedule (Ages 15+ Years)

• For individuals initiating vaccination at age 15 years or older, administer 3 doses at 0,1–2, and 6 months 1, 2, 6, 3
• Minimum intervals: 4 weeks between doses 1 and 2, and 12 weeks between doses 2 and 3 2, 6, 3
• The minimum interval between the first and last dose must be 24 weeks (6 months) 4

Critical principle: The age at which the first dose is given determines the schedule—not when subsequent doses are administered. A patient who started at age 14 qualifies for the 2-dose schedule even if the second dose is delayed beyond age 15. 2

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Catch-Up Vaccination

• Catch-up vaccination is recommended for all persons through age 26 years who are not adequately vaccinated 2, 3
• This includes females aged 13–26 years and males aged 13–21 years not previously vaccinated or with incomplete series 3
• Males aged 22–26 years may be vaccinated, though providers should inform them that vaccination at older ages may be less effective due to likely prior HPV exposure 1, 3

Interrupted Schedules

• The vaccine series does not need to be restarted regardless of how long the interruption lasts between doses 2, 3
• If interrupted, administer the next dose as soon as possible, maintaining minimum intervals (4 weeks between doses 1–2; 12 weeks between doses 2–3) 2, 6
• There is no maximum time interval between doses—the vaccine does not "expire" or lose effectiveness if doses are delayed 2

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Adults Aged 27–45 Years

• In October 2018, the FDA approved Gardasil 9 for men and women aged 26 to 45 years 1
• Shared clinical decision-making is recommended for some adults aged 27–45 years who are not adequately vaccinated 3
• Most sexually active adults in this age range have already been exposed to HPV, and vaccine effectiveness is lower due to prior infections 3
• However, the vaccine still protects against HPV types not yet acquired, and prior HPV exposure (history of genital warts, abnormal Pap tests, or positive HPV DNA tests) does not contraindicate vaccination 2, 7

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Special Populations

Immunocompromised Individuals

• All immunocompromised persons require a 3-dose schedule regardless of age at initiation 1, 2, 6, 3
• This includes HIV-positive individuals, solid organ transplant recipients, and others with immunocompromising conditions 2, 6, 3
• Seroconversion rates in transplant recipients are lower (53–68% per HPV type) compared to immunocompetent individuals 2
• Both bivalent and quadrivalent HPV vaccines result in high antibody responses in people living with HIV, maintained for up to 24 months 8

Men Who Have Sex with Men (MSM)

• Routine vaccination is recommended through age 26 years for MSM if not previously vaccinated 2, 3

Males

• All males should receive routine HPV vaccination starting at age 11–12 years 2
• The quadrivalent vaccine reduces external genital lesions and anogenital warts in males (rate ratio 0.11 for anogenital warts, 95% CI 0.03 to 0.38) 8
• HPV vaccination prevents anal cancer (89% HPV-associated), penile cancer (63% HPV-associated), and oropharyngeal cancer (72% HPV-associated in males) 2

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Pregnancy and Lactation

• Vaccination is not recommended during pregnancy; if a woman becomes pregnant during the vaccination series, subsequent doses should be postponed until after delivery 2, 3
• Breastfeeding women can safely receive the HPV vaccine 2, 3

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Contraindications and Precautions

• History of immediate hypersensitivity to yeast or any vaccine component is a contraindication 2
• Vaccination should be deferred for people with moderate or severe acute illness 2
• Patients should sit or lie down for 15 minutes after vaccination due to risk of syncope in adolescents 2
• The most common adverse event is injection-site reactions (pain, redness), occurring in approximately 60% of recipients 8

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Current Vaccine Available

• Gardasil 9 (9-valent HPV vaccine) is the only HPV vaccine currently distributed in the United States as of January 2017 1, 6, 3
• It protects against HPV types 6,11,16,18,31,33,45,52, and 58 1, 6, 3
• HPV types 16 and 18 are responsible for approximately 70% of HPV-related cancers 6
• The nonavalent vaccine can prevent up to an additional 14% of anogenital cancers and up to 30% of high-risk precancerous cervical lesions compared to quadrivalent vaccine 1, 4

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Important Clinical Considerations

No Prevaccination Testing Required

• No prevaccination testing is recommended before vaccination, including no Pap smear, HPV testing, or antibody testing 2, 3

Timing for Maximum Effectiveness

• Vaccination is most effective when given before exposure to HPV through sexual activity 2, 6, 3
• Approximately 24% of adolescents report sexual intercourse by 9th grade, and 58.1% by 12th grade 2
• HPV infection incidence is nearly 60% within 2 years after sexual initiation in males 2
• However, sexually active individuals should still be vaccinated according to age-based recommendations, as they are unlikely to have been infected with all vaccine HPV types 2, 6

Cervical Cancer Screening

• All women, regardless of vaccination status, should continue to follow cervical cancer screening guidelines 1, 2, 6, 3
• The vaccine does not protect against all oncogenic HPV types, and screening remains essential 2
• Women with abnormal Pap test results can receive the HPV vaccine, though they should be informed that vaccination does not protect against already acquired infections 2

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Cancer Prevention Impact

• HPV vaccination can prevent approximately 28,500 to 31,200 cancers annually in the United States 1, 3
• This includes virtually all cervical cancers, 90% of anal cancers, 70% of oropharyngeal cancers, and 60–70% of vaginal, vulvar, and penile cancers 1
• The vaccine prevents approximately 90% of genital warts (caused by HPV types 6 and 11) 1, 2, 4

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Common Pitfalls to Avoid

• Do not restart the series if interrupted—continue from where you left off, maintaining minimum intervals 2, 3
• Do not delay vaccination waiting for "optimal" timing—early vaccination before sexual debut is critical 2
• Do not withhold vaccination from sexually active individuals—they can still benefit from protection against HPV types not yet acquired 2, 6
• Do not perform prevaccination testing—it is unnecessary and delays vaccination 2, 3
• Remember that the age at first dose determines the schedule, not the age at subsequent doses 2