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NCT Number: NCT04688476

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

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.

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This study is active but is not currently recruiting participants.

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Key information

Conditions

HPV-associated Cancer

Sex eligibility

All sexes

Study type

Observational

Primary location

University of Arizona, Tucson, Arizona, United States

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Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

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.

Treatment and study plan

Primary outcomes

  1. 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

Secondary outcomes

  1. 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

Sponsors and collaborators

Lead sponsor

University of Arizona

Other

Collaborators

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

Registry information

Important dates

Study start
2020
Primary completion
2025
Study completion
2025
First posted
Dec 30, 2020
Registry last updated
Oct 16, 2025

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

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This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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