The investigators propose the study titled "Efficacy of booster injection with Gardasil-9 vaccine on intersurgical interval (ISI) for adults with recurrent respiratory papillomatosis (RRP)".

Recurrent respiratory papillomatosis (RRP) is a human papilloma virus (HPV) mediated disease of recurrent benign papillomas within the aerodigestive tract. While the foundation of treatment remains surgical debulking and occasionally adjuvant therapies such as cidofovir and bevacizumab, there remains a population of patients suffering from aggressive disease recurrence despite treatment.

Multiple studies have demonstrated treatment benefit in the form of an increase in intersurgical interval (ISI), following Gardasil vaccination. While adjuvant vaccination has favorably reduced recurrence of RRP and improved time course of disease recurrence for previously unvaccinated RRP patients, there remains a clinical population of adult patients suffering from persistent RRP that have previously undergone the Gardasil 3-vaccine series. Additionally, recent studies suggest a waning effect of Gardasil vaccination on ISI at longer time points.

Therefore, the investigators propose administering GARDASIL®9 (Human Papillomavirus 9-valent Vaccine, Recombinant) 0.5-mL suspension for injection as a one-time "booster" dose to adult patients >18 years of age, who have previously completed the 3-course vaccination series.

Inclusion Criteria:

1. Age > 18 years old
2. Has completed the 2- or 3-course Gardasil-9 vaccine series >2 years ago
3. Has a diagnosis of recurrent respiratory papillomatosis
4. Continue to have disease recurrence
5. Have at least 2 interventions (in order to calculate ISI)

Exclusion Criteria:

• Those who have not had at least two interventions prior to booster administration (inability to calculate ISI prior to 2- or 3-dose Gardasil-9 vaccine series and after completion of the vaccine series)
• Patients who have had no interventions for their disease since vaccination (unable to calculate post-Gardasil 2- or 3-dose vaccine series ISI)
• Have not completed the Gardasil-9 2- or 3-dose vaccine series greater than 2 years prior to proposed booster (not enough follow-up time to assess disease severity since vaccination)
• Patients with active any HPV-related cancer - their treatment course may impact the data collected during the study duration
• Any individual who has experienced anaphylaxis or hypersensitivity to a previous Gardasil vaccine (participation in this study would not be safe for the patient)