If someone missed their last Gardasil 9 (Human Papillomavirus 9-valent Vaccine) shot at 6 months and it's been over a year since the last vaccine, do they need to restart the series?

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Last updated: June 8, 2025View editorial policy

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From the Research

No, if someone missed their last Gardasil 9 shot at 6 months and it's been over a year since their previous dose, they do not need to restart the HPV vaccination series. They should simply get the missed third dose as soon as possible to complete the series. The most recent guidance from the National Advisory Committee on Immunization (NACI) 1 does not specifically address the issue of missed doses, but it does emphasize the importance of completing the vaccination series for full protection against HPV types covered by the vaccine. According to the CDC, interrupted HPV vaccine schedules do not need to be restarted; there is no maximum interval between doses 1. The immune system has a "memory" from the previous doses, and the final dose will still effectively boost immunity even after a delay. For the standard three-dose schedule (typically given at 0,2, and 6 months), completing all doses is important for full protection against HPV types covered by the vaccine, even if the timing is not perfect. Some key points to consider:

  • The person should contact their healthcare provider to schedule the missed dose, and once they receive it, they will be considered fully vaccinated against HPV.
  • The NACI updated recommendations for individuals 9 to 20 years of age to receive one dose of 9vHPV (Gardasil-9, Merck) vaccine 1.
  • Individuals 21 years of age and older should receive a 2-dose schedule, and those considered immunocompromised and individuals infected with HIV should receive a 3-dose series 1. However, these recommendations do not directly address the issue of missed doses, and the general principle of completing the series as soon as possible still applies. It's worth noting that other studies have shown the effectiveness of HPV vaccination in reducing the incidence of HPV-related diseases, such as cervical cancer 2 and oropharyngeal carcinoma 3, but these studies do not specifically address the issue of missed doses. Overall, the most important thing is to complete the vaccination series as soon as possible to ensure full protection against HPV types covered by the vaccine.

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This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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