An Extended Follow-Up Study of the HPV Vaccine Delayed Booster Trial

October 14, 2025 updated by: Sherry Chow, University of Arizona

This is an extended follow-up study to follow-up study participants who received 1 booster dose of Gardasil 9 in the "HPV vaccine delayed booster trial." This was a prospective, single-arm, open-label, non-randomized, phase IIa trial among 9-11 year-old girls and boys to determine the immunogenicity after a single dose of the nonavalent HPV vaccine (Gardasil 9) over 24 months, with a delayed booster dose at 24 months and an optional booster at 30 months after the first dose. Participants provided blood specimens at 6, 12, 18, 24, and 30 months after the first dose. Serologic geometric mean titers (GMT) of the nine vaccine types (HPV 16/18/ 6/11/31/33/45/52/58) were measured at each time point. One hundred and thirty-three (133) participants received one booster dose at month 24 and elected not to receive the second booster at month 30.

For this follow-up study, we anticipate that we will be able to accrue 120 participants from the original study who received just one booster dose. Participants who received one booster dose of Gardasil 9 will be contacted to return to the clinic to provide blood specimens at 48 (±3), 60 (±3), and 72 (±3) months after the priming dose. Serologic geometric mean titers (GMT) of the nine vaccine types (HPV 16/18/ 6/11/31/33/45/52/58) will be measured at each time point.

Study Overview

Status

Active, not recruiting

Conditions

Study Type

Observational

Enrollment (Actual)

113

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • United States
    • Arizona
      • Tucson, Arizona, United States, 85724
        • University of Arizona
    • California
      • Los Angeles, California, United States, 90095
        • University of California, Los Angeles

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Child
  • Adult
  • Older Adult

Accepts Healthy Volunteers

Yes

Sampling Method

Non-Probability Sample

Study Population

Study population is restricted to study participants who received one booster dose of Gardasil 9 at month 24 and elected not to receive the second booster at month 30 in the original "HPV vaccine delayed booster trial".

Description

Inclusion Criteria:

  • Study participants who received one booster dose of Gardasil 9 at month 24 and elected not to receive the second booster at month 30 in the original "HPV vaccine delayed booster trial"
  • Ability to understand and the willingness to sign a written informed consent document by the legal representative(s) of the participant.
  • Ability to understand and the willingness to sign a written assent document by the participant.

Exclusion Criteria:

- Has received any HPV vaccine dose from an external source at any point during or after participation in the HPV vaccine delayed booster trial.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Time Frame
The differences in geometric mean titer (GMT) of HPV 16 and HPV18 between 30 vs. 48, 48 vs. 60, and 60 vs. 72 months after the priming dose of Gardasil
Time Frame: 72 months
72 months

Secondary Outcome Measures

Outcome Measure
Time Frame
The differences in geometric mean titer of other HPV types (HPV6/11/31/33/45/52/58) between 30 vs. 48, 48 vs. 60, and 60 vs. 72 months after the priming dose of Gardasil 9
Time Frame: 72 months
72 months

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

University of Arizona

Collaborators

National Cancer Institute (NCI)
University of California, Los Angeles

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

November 17, 2020

Primary Completion (Actual)

September 9, 2025

Study Completion (Estimated)

December 1, 2025

Study Registration Dates

First Submitted

December 17, 2020

First Submitted That Met QC Criteria

December 23, 2020

First Posted (Actual)

December 30, 2020

Study Record Updates

Last Update Posted (Estimated)

October 16, 2025

Last Update Submitted That Met QC Criteria

October 14, 2025

Last Verified

September 1, 2025

More Information

Terms related to this study

Other Study ID Numbers

  • 2007882387
  • UG1 242596 (Other Grant/Funding Number: DCP)

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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