Gardasil-9 Dosing Interval
For a 2-dose schedule of Gardasil-9, the second dose should be administered 6 months after the first dose. 1
Standard Dosing Schedules by Age
Two-Dose Schedule (Ages 9-14 years)
- The CDC recommends a 2-dose schedule for individuals initiating vaccination before their 15th birthday 1
- The second dose is administered 6 months after the first dose 2, 1
- A 12-month interval between 2 doses produces a more robust immune response than a 6-month interval, though 6 months remains the standard recommendation 1
- Geometric mean antibody titers are higher in the 9-14 year age group compared to older adolescents and young adults, supporting the 2-dose regimen 1
Three-Dose Schedule (Ages 15-26 years and older)
- A 3-dose series is required for individuals initiating vaccination at age 15 years or older 1
- Dose 2 should be given 1-2 months after dose 1 2, 1
- Dose 3 should be administered 6 months after dose 1 2, 1
- The minimum interval is 24 weeks between the first and third doses 1
Special Populations Requiring Three Doses
Immunocompromised Individuals
- Persons with immunocompromising conditions require a 3-dose series regardless of age at initiation 1, 3
- This includes individuals with HIV infection 2
- The standard 3-dose schedule applies: 0,1-2 months, and 6 months 1
Important Considerations
Interrupted Schedules
- If the vaccine series is interrupted, it does not need to be restarted 1
- After interruption following the first dose, the second dose should be administered as soon as possible 1
- A minimum interval of at least 12 weeks must be maintained between the second and third doses 1
Recent Updates
- Recent Canadian guidance (2024) now supports a 1-dose schedule for ages 9-20 years, though this represents newer evidence not yet universally adopted 3
- For individuals 21 years and older in the Canadian guidelines, a 2-dose schedule is recommended 3