CompletedNCT03943875Updated Apr 16, 2026Results posted

GARDASIL 9: 3 Dose vs. 2 Dose With Delayed 3rd Dose

A Phase 4 interventional study of 9-valent HPV vaccine, 2 dose efficacy and 9-valent HPV vaccine, 3 doses standard timing in Immunization, Efficacy and Human Papilloma Virus, sponsored by The University of Texas Medical Branch, Galveston. Completed at 1 site in United States. Open to participants aged 15 Years to 26 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-04-16.

Sponsored by The University of Texas Medical Branch, Galveston · Phase 4, Interventional, and Other

Phase: Phase 4
Study type: Interventional
Enrollment: 767
Allocation: Randomized
Ages: 15 Years to 26 Years
Sex: All

Study summary

The investigators are evaluating whether 15-26 year old males and females need a 3rd dose of the human papillomavirus (HPV) vaccine, or whether 2 doses provide similar protection as 3 doses from the 9 types of HPV that it protects against.

Read the detailed description

The investigators are studying an amended dosing regimen of an approved drug (Gardasil 9) in the population for which it is approved (vaccine is approved for ages 9-45 years and participants in this study will be 15-26 years of age.) The purpose of the study is to examine a delayed dosing schedule. The current recommendation is to administer the vaccine in 3 doses (administered at 0, 1-2 months and 6 months) to those 15-26 years of age but only 2 doses (0 and 6 months) if given at 9-14 years of age. The investigators will conduct a randomized study to determine if 2 doses will elicit an immune response similar to the standard 3 doses in those 15-26 years of age. Participants in the study group will receive 2 doses of Gardasil 9 at 0 and 6 months. Participants in the control group will receive 3 doses of Gardasil 9 at 0, 1-2 months and 6 months. All participants (Target Accrual n=512) will have 5 mLs of blood drawn at 0, 7, and 12 months. Following the 12 month blood draw, participants randomized to 2-doses will receive the 3rd dose. Potential participants will be recruited in the University of Texas Medical Branch (UTMB) clinics where providers have given the PI permission to directly contact patients. The investigators will also display signs and use email announcements at UTMB and other college campuses and will advertise the study online or by mail. The investigators will call UTMB patients if their provider gave permission to contact the patient, or if the patients gave prior consent to contact through the UTMB system. Potential participants (and their parents, if under 18 years of age) will be screened with inclusion/exclusion criteria. Eligible and interested parents and patients will sign informed written consent. Patients under 18 years of age will sign written assent. At the initial visit, eligible, consented participants will have their blood drawn, be randomized into either the study or control group, and receive a dose of the HPV vaccine. Participants will be re-screened against the inclusion/exclusion criteria at subsequent visits. All participants will receive compensation administered through a ClinCard following each of the 3 blood draws.

Conditions studied

Immunization
Efficacy
Human Papilloma Virus

Keywords

HPV vaccination
Gardasil 9
vaccine efficacy

In context

Lead sponsor

The University of Texas Medical Branch, Galveston is the lead sponsor of 251 studies on the registry; 38 are open to participants now.

Of its 30 completed or terminated interventional studies of FDA-regulated products, 25 (83%) have results posted.

Counted across the registry records on this site, refreshed daily.

Who can participate

Ages eligible: 15 Years to 26 Years
Sexes eligible: All
Accepts healthy volunteers: Yes

Inclusion criteria

Males and females 15-26 years old.
Ability to give informed consent. All participants under 18 years of age must have the informed consent of a parent and must assent to participation.
Has not received any prior doses of the HPV vaccine. Investigators will ask the patient and his/her parent (if \<18) about prior vaccination and check the state registry (Immtrac), as well as the UTMB electronic medical record (if previously seen at UTMB), investigators will check with their primary care provider, if feasible, for patients who are not a previously established UTMB patient.
Identified source of funding for vaccine which may include Texas Vaccines for Children (VFC) program, Medicaid, the Children's Health Insurance Plan (CHIP), Texas Healthy Women program or other public or private health insurance.
Reliable telephone access.
Participant and parent/ guardian (if \<18) can read and speak either English or Spanish.

Exclusion criteria

Exclusion Criteria:

For females, currently pregnant or plans to become pregnant or donate eggs in next 12 months. Sexually active females must report that they use regular birth control. All female subjects will be required to take a urine pregnancy test before each Gardasil 9 dose, unless it can be verified that she gave birth within the last week. Any subjects with positive tests at the initial visit will be disqualified from the study and advised to seek prenatal care. If a subject is pregnant when her follow-up visit window closes, she will be removed from the study.
History of 6 or more lifetime sexual partners.
History of any immunodeficiencies (HIV+, chemotherapy treatment, status splenectomy) or autoimmune disorders (lupus, thyroid disorder, psoriasis).
History of bleeding or platelet disorders such as hemophilia.
Currently taking medication which can suppress immune function including systemic corticosteroids, radiation therapy, cyclophosphamide, azathioprine, methotrexate, cyclosporine, leflunomide, TNF-alpha antagonists, monoclonal antibody therapies, or intravenous immunoglobulin treatment.
Known allergies to any components of the vaccine, including aluminum, yeast or Benzonase.
Febrile at ≥100°F in the 24 hours prior to vaccination. This will be reviewed before each Gardasil 9 dose.
Received any non-study inactive vaccines within the past 14 days or any live vaccines within the past 30 days. Those excluded for this reason will be re-screened under the same study number at a later date.
Plan to move out of the Galveston/Houston area in the 13 months following study entry.

Study design

Phase: Phase 4
Primary purpose: Other
Allocation: Randomized
Intervention model: Parallel assignment
Masking: Single (Outcomes assessor)
Enrollment: 767 participants (actual)

Study arms

Active comparator
Females, 3 dose standard
Three doses of the 9-valent HPV vaccine to be administered to the comparison group (15-26 years of age) at 0, 2, and 6 months.
Biological: 9-valent HPV vaccine, 3 doses standard timing
Experimental
Females, 2 dose with delayed 3rd dose
Two doses of the 9-valent HPV vaccine to be administered to the experimental group (15-26 years of age) at 0 and 6 months. Additional HPV vaccine dose will be offered after final blood draw at 12 months.
Biological: 9-valent HPV vaccine, 2 dose efficacy
Active comparator
Males, 3 dose standard
Three doses of the 9-valent HPV vaccine to be administered to the comparison group (15-26 years of age) at 0, 2, and 6 months.
Biological: 9-valent HPV vaccine, 3 doses standard timing
Experimental
Males, 2 dose with delayed 3rd dose
Two doses of the 9-valent HPV vaccine to be administered to the experimental group (15-26 years of age) at 0 and 6 months. Additional HPV vaccine dose will be offered after final blood draw at 12 months.
Biological: 9-valent HPV vaccine, 2 dose efficacy

Interventions

Biological9-valent HPV vaccine, 2 dose efficacy
Evaluate the efficacy of 2 doses of the HPV vaccine across a 12 month period following the 1st dose among 15-26 year old males and females.
Biological9-valent HPV vaccine, 3 doses standard timing
Will be comparison group for 2 dose efficacy group.

What researchers measure

Primary outcomes

Short-term Human Papillomavirus (HPV) Type-specific Antibody Response for Type HPV-6
Yes/No for seroconversion, defined as changing from seronegative (no detectable antibodies) to seropositive (antibodies at or exceeding natural immunity levels) to HPV type 6, measured as % of participants who seroconvert
Time frame: Month 7
Short-term HPV Type-specific Antibody Response for Type HPV-11
Yes/No for seroconversion, defined as changing from seronegative (no detectable antibodies) to seropositive (antibodies at or exceeding natural immunity levels) to HPV type 11, measured as measured as % of participants who seroconvert.
Time frame: Month 7
Short-term HPV Type-specific Antibody Response for Type HPV-16
Yes/No for seroconversion, defined as changing from seronegative (no detectable antibodies) to seropositive (antibodies at or exceeding natural immunity levels) to HPV type 16, measured as % of participants who seroconvert
Time frame: Month 7
Short-term HPV Type-specific Antibody Response for Type HPV-18
Yes/No for seroconversion, defined as changing from seronegative (no detectable antibodies) to seropositive (antibodies at or exceeding natural immunity levels) to HPV type 18, measured as % of participants who seroconvert
Time frame: Month 7
Short-term HPV Type-specific Antibody Response for Type HPV-31
Yes/No for seroconversion, defined as changing from seronegative (no detectable antibodies) to seropositive (antibodies at or exceeding natural immunity levels) to HPV type 31, measured as % of participants who seroconvert
Time frame: Month 7
Short-term HPV Type-specific Antibody Response for Type HPV-33
Yes/No for seroconversion, defined as changing from seronegative (no detectable antibodies) to seropositive (antibodies at or exceeding natural immunity levels) to HPV type 33, measured as % of participants who seroconvert
Time frame: Month 7
Short-term HPV Type-specific Antibody Response for Type HPV-45
Yes/No for seroconversion, defined as changing from seronegative (no detectable antibodies) to seropositive (antibodies at or exceeding natural immunity levels) to HPV type 45, measured as % of participants who seroconvert
Time frame: Month 7
Short-term HPV Type-specific Antibody Response for Type HPV-52
Yes/No for seroconversion, defined as changing from seronegative (no detectable antibodies) to seropositive (antibodies at or exceeding natural immunity levels) to HPV type 52, measured as % of participants who seroconvert
Time frame: Month 7
Short-term HPV Type-specific Antibody Response for Type HPV-58
Yes/No for seroconversion, defined as changing from seronegative (no detectable antibodies) to seropositive (antibodies at or exceeding natural immunity levels) to HPV type 58, measured as % of participants who seroconvert
Time frame: Month 7
HPV Type-specific Antibody Response for Type HPV-6
Yes/No for seroconversion, defined as changing from seronegative (no detectable antibodies) to seropositive (antibodies at or exceeding natural immunity levels) to HPV type 6, measured as % of participants who seroconvert
Time frame: Month 12
HPV Type-specific Antibody Response for Type HPV-11
Yes/No for seroconversion, defined as changing from seronegative (no detectable antibodies) to seropositive (antibodies at or exceeding natural immunity levels) to HPV type 11, measured as % of participants who seroconvert
Time frame: Month 12
HPV Type-specific Antibody Response for Type HPV-16
Yes/No for seroconversion, defined as changing from seronegative (no detectable antibodies) to seropositive (antibodies at or exceeding natural immunity levels) to HPV type 16, measured as % of participants who seroconvert
Time frame: Month 12
HPV Type-specific Antibody Response for Type HPV-18
Yes/No for seroconversion, defined as changing from seronegative (no detectable antibodies) to seropositive (antibodies at or exceeding natural immunity levels) to HPV type 18, measured as % of participants who seroconvert
Time frame: Month 12
HPV Type-specific Antibody Response for Type HPV-31
Yes/No for seroconversion, defined as changing from seronegative (no detectable antibodies) to seropositive (antibodies at or exceeding natural immunity levels) to HPV type 31, measured as % of participants who seroconvert
Time frame: Month 12
HPV Type-specific Antibody Response for Type HPV-33
Yes/No for seroconversion, defined as changing from seronegative (no detectable antibodies) to seropositive (antibodies at or exceeding natural immunity levels) to HPV type 33, measured as % of participants who seroconvert
Time frame: Month 12
HPV Type-specific Antibody Response for Type HPV-45
Yes/No for seroconversion, defined as changing from seronegative (no detectable antibodies) to seropositive (antibodies at or exceeding natural immunity levels) to HPV type 45, measured as % of participants who seroconvert
Time frame: Month 12
HPV Type-specific Antibody Response for Type HPV-52
Yes/No for seroconversion, defined as changing from seronegative (no detectable antibodies) to seropositive (antibodies at or exceeding natural immunity levels) to HPV type 52, measured as % of participants who seroconvert
Time frame: Month 12
HPV Type-specific Antibody Response for Type HPV-58
Yes/No for seroconversion, defined as changing from seronegative (no detectable antibodies) to seropositive (antibodies at or exceeding natural immunity levels) to HPV type 58, measured as % of participants who seroconvert
Time frame: Month 12

Results

Posted Feb 17, 2026

Participant flow

Participant flow — Overall Study
Milestone	Females, 3 Dose Standard	Females, 2 Dose With Delayed 3rd Dose	Males, 3 Dose Standard	Males, 2 Dose With Delayed 3rd Dose
Started	221	217	165	164
Completed	168	173	140	130
Not completed	53	44	25	34
Withdrew: Withdrawal by subject	14	6	6	3
Withdrew: Lost to follow-up	12	13	6	9
Withdrew: Pregnancy	9	6	0	0
Withdrew: Protocol violation	3	4	10	11
Withdrew: Moved	15	15	3	11

Outcome measures

PrimaryShort-term Human Papillomavirus (HPV) Type-specific Antibody Response for Type HPV-6

Yes/No for seroconversion, defined as changing from seronegative (no detectable antibodies) to seropositive (antibodies at or exceeding natural immunity levels) to HPV type 6, measured as % of participants who seroconvert

Time frame:: Month 7
Reported as:: Number · % of participants with seroconversion

Short-term Human Papillomavirus (HPV) Type-specific Antibody Response for Type HPV-6
% of participants with seroconversion	Females, 3 Dose Standard	Females, 2 Dose With Delayed 3rd Dose	Males, 3 Dose Standard	Males, 2 Dose With Delayed 3rd Dose
Short-term Human Papillomavirus (HPV) Type-specific Antibody Response for Type HPV-6	99.25 (95.88 to 99.98)	100.00 (97.26 to 100.000)	100.00 (97.05 to 100.00)	100.00 (96.73 to 100.00)

PrimaryShort-term HPV Type-specific Antibody Response for Type HPV-11

Time frame:: Month 7
Reported as:: Number · % of participants with seroconversion

Short-term HPV Type-specific Antibody Response for Type HPV-11
% of participants with seroconversion	Females, 3 Dose Standard	Females, 2 Dose With Delayed 3rd Dose	Males, 3 Dose Standard	Males, 2 Dose With Delayed 3rd Dose
Short-term HPV Type-specific Antibody Response for Type HPV-11	99.25 (95.91 to 99.98)	100.00 (97.32 to 100.00)	100.00 (97.07 to 100.00)	100.00 (96.73 to 100.00)

PrimaryShort-term HPV Type-specific Antibody Response for Type HPV-16

Time frame:: Month 7
Reported as:: Number · % of participants with seroconversion

Short-term HPV Type-specific Antibody Response for Type HPV-16
% of participants with seroconversion	Females, 3 Dose Standard	Females, 2 Dose With Delayed 3rd Dose	Males, 3 Dose Standard	Males, 2 Dose With Delayed 3rd Dose
Short-term HPV Type-specific Antibody Response for Type HPV-16	99.15 (95.37 to 99.98)	100.00 (97.00 to 100.00)	100.00 (96.76 to 100.00)	100.00 (96.48 to 100.00)

PrimaryShort-term HPV Type-specific Antibody Response for Type HPV-18

Time frame:: Month 7
Reported as:: Number · % of participants with seroconversion

Short-term HPV Type-specific Antibody Response for Type HPV-18
% of participants with seroconversion	Females, 3 Dose Standard	Females, 2 Dose With Delayed 3rd Dose	Males, 3 Dose Standard	Males, 2 Dose With Delayed 3rd Dose
Short-term HPV Type-specific Antibody Response for Type HPV-18	99.29 (96.08 to 99.98)	100.00 (97.26 to 100.00)	100.00 (97.02 to 100.00)	100.00 (96.84 to 100.00)

PrimaryShort-term HPV Type-specific Antibody Response for Type HPV-31

Time frame:: Month 7
Reported as:: Number · % of participants with seroconversion

Short-term HPV Type-specific Antibody Response for Type HPV-31
% of participants with seroconversion	Females, 3 Dose Standard	Females, 2 Dose With Delayed 3rd Dose	Males, 3 Dose Standard	Males, 2 Dose With Delayed 3rd Dose
Short-term HPV Type-specific Antibody Response for Type HPV-31	99.29 (96.11 to 99.98)	100.00 (97.34 to 100.00)	100.00 (97.09 to 100.00)	100.00 (96.97 to 100.00)

PrimaryShort-term HPV Type-specific Antibody Response for Type HPV-33

Time frame:: Month 7
Reported as:: Number · % of participants with seroconversion

Short-term HPV Type-specific Antibody Response for Type HPV-33
% of participants with seroconversion	Females, 3 Dose Standard	Females, 2 Dose With Delayed 3rd Dose	Males, 3 Dose Standard	Males, 2 Dose With Delayed 3rd Dose
Short-term HPV Type-specific Antibody Response for Type HPV-33	99.35 (96.44 to 99.98)	100.00 (97.60 to 100.00)	100.00 (97.20 to 100.00)	100.00 (97.09 to 100.00)

PrimaryShort-term HPV Type-specific Antibody Response for Type HPV-45

Time frame:: Month 7
Reported as:: Number · % of participants with seroconversion

Short-term HPV Type-specific Antibody Response for Type HPV-45
% of participants with seroconversion	Females, 3 Dose Standard	Females, 2 Dose With Delayed 3rd Dose	Males, 3 Dose Standard	Males, 2 Dose With Delayed 3rd Dose
Short-term HPV Type-specific Antibody Response for Type HPV-45	99.36 (96.48 to 99.98)	100.00 (97.62 to 100.00)	100.00 (97.14 to 100.00)	100.00 (97.09 to 100.00)

PrimaryShort-term HPV Type-specific Antibody Response for Type HPV-52

Time frame:: Month 7
Reported as:: Number · % of participants with seroconversion

Short-term HPV Type-specific Antibody Response for Type HPV-52
% of participants with seroconversion	Females, 3 Dose Standard	Females, 2 Dose With Delayed 3rd Dose	Males, 3 Dose Standard	Males, 2 Dose With Delayed 3rd Dose
Short-term HPV Type-specific Antibody Response for Type HPV-52	99.22 (95.76 to 99.98)	100.00 (97.20 to 100.00)	100.00 (96.76 to 100.00)	100.00 (96.61 to 100.00)

PrimaryShort-term HPV Type-specific Antibody Response for Type HPV-58

Time frame:: Month 7
Reported as:: Number · % of participants with seroconversion

Short-term HPV Type-specific Antibody Response for Type HPV-58
% of participants with seroconversion	Females, 3 Dose Standard	Females, 2 Dose With Delayed 3rd Dose	Males, 3 Dose Standard	Males, 2 Dose With Delayed 3rd Dose
Short-term HPV Type-specific Antibody Response for Type HPV-58	99.31 (96.22 to 99.98)	100.00 (97.40 to 100.00)	100.00 (97.11 to 100.00)	100.00 (97.00 to 100.00)

PrimaryHPV Type-specific Antibody Response for Type HPV-6

Time frame:: Month 12
Reported as:: Number · % of participants with seroconversion

HPV Type-specific Antibody Response for Type HPV-6
% of participants with seroconversion	Females, 3 Dose Standard	Females, 2 Dose With Delayed 3rd Dose	Males, 3 Dose Standard	Males, 2 Dose With Delayed 3rd Dose
HPV Type-specific Antibody Response for Type HPV-6	100.00 (97.11 to 100.00)	100.00 (97.14 to 100.00)	100.00 (96.95 to 100.00)	99.06 (94.86 to 99.98)

PrimaryHPV Type-specific Antibody Response for Type HPV-11

Time frame:: Month 12
Reported as:: Number · % of participants with seroconversion

HPV Type-specific Antibody Response for Type HPV-11
% of participants with seroconversion	Females, 3 Dose Standard	Females, 2 Dose With Delayed 3rd Dose	Males, 3 Dose Standard	Males, 2 Dose With Delayed 3rd Dose
HPV Type-specific Antibody Response for Type HPV-11	100.00 (97.14 to 100.00)	100.00 (97.20 to 100.00)	100.00 (96.97 to 100.00)	100.00 (96.58 to 100.00)

PrimaryHPV Type-specific Antibody Response for Type HPV-16

Time frame:: Month 12
Reported as:: Number · % of participants with seroconversion

HPV Type-specific Antibody Response for Type HPV-16
% of participants with seroconversion	Females, 3 Dose Standard	Females, 2 Dose With Delayed 3rd Dose	Males, 3 Dose Standard	Males, 2 Dose With Delayed 3rd Dose
HPV Type-specific Antibody Response for Type HPV-16	100.00 (96.82 to 100.00)	100.00 (96.84 to 100.00)	100.00 (96.67 to 100.00)	100.00 (96.31 to 100.00)

PrimaryHPV Type-specific Antibody Response for Type HPV-18

Time frame:: Month 12
Reported as:: Number · % of participants with seroconversion

HPV Type-specific Antibody Response for Type HPV-18
% of participants with seroconversion	Females, 3 Dose Standard	Females, 2 Dose With Delayed 3rd Dose	Males, 3 Dose Standard	Males, 2 Dose With Delayed 3rd Dose
HPV Type-specific Antibody Response for Type HPV-18	99.24 (95.85 to 99.98)	98.43 (94.43 to 99.81)	100.00 (96.35 to 100.00)	99.09 (94.34 to 99.99)

PrimaryHPV Type-specific Antibody Response for Type HPV-31

Time frame:: Month 12
Reported as:: Number · % of participants with seroconversion

HPV Type-specific Antibody Response for Type HPV-31
% of participants with seroconversion	Females, 3 Dose Standard	Females, 2 Dose With Delayed 3rd Dose	Males, 3 Dose Standard	Males, 2 Dose With Delayed 3rd Dose
HPV Type-specific Antibody Response for Type HPV-31	100.00 (97.26 to 100.00)	100.00 (97.2 to 100.00)	100.00 (97.00 to 100.00)	99.13 (95.25 to 99.98)

PrimaryHPV Type-specific Antibody Response for Type HPV-33

Time frame:: Month 12
Reported as:: Number · % of participants with seroconversion

HPV Type-specific Antibody Response for Type HPV-33
% of participants with seroconversion	Females, 3 Dose Standard	Females, 2 Dose With Delayed 3rd Dose	Males, 3 Dose Standard	Males, 2 Dose With Delayed 3rd Dose
HPV Type-specific Antibody Response for Type HPV-33	99.31 (96.19 to 99.98)	100.00 (97.45 to 100.00)	100.00 (97.11 to 100.00)	99.17 (95.44 to 99.98)

PrimaryHPV Type-specific Antibody Response for Type HPV-45

Time frame:: Month 12
Reported as:: Number · % of participants with seroconversion

HPV Type-specific Antibody Response for Type HPV-45
% of participants with seroconversion	Females, 3 Dose Standard	Females, 2 Dose With Delayed 3rd Dose	Males, 3 Dose Standard	Males, 2 Dose With Delayed 3rd Dose
HPV Type-specific Antibody Response for Type HPV-45	98.66 (95.24 to 99.84)	97.92 (94.03 to 99.57)	99.18 (95.52 to 99.98)	95.00 (89.43 to 98.14)

PrimaryHPV Type-specific Antibody Response for Type HPV-52

Time frame:: Month 12
Reported as:: Number · % of participants with seroconversion

HPV Type-specific Antibody Response for Type HPV-52
% of participants with seroconversion	Females, 3 Dose Standard	Females, 2 Dose With Delayed 3rd Dose	Males, 3 Dose Standard	Males, 2 Dose With Delayed 3rd Dose
HPV Type-specific Antibody Response for Type HPV-52	100.00 (97.02 to 100.00)	100.00 (97.07 to 100.00)	100.00 (96.64 to 100.00)	100.00 (96.48 to 100.00)

PrimaryHPV Type-specific Antibody Response for Type HPV-58

Time frame:: Month 12
Reported as:: Number · % of participants with seroconversion

HPV Type-specific Antibody Response for Type HPV-58
% of participants with seroconversion	Females, 3 Dose Standard	Females, 2 Dose With Delayed 3rd Dose	Males, 3 Dose Standard	Males, 2 Dose With Delayed 3rd Dose
HPV Type-specific Antibody Response for Type HPV-58	99.27 (96.00 to 99.98)	100.00 (97.22 to 100.00)	100.00 (97.02 to 100.00)	99.14 (95.29 to 99.98)

Adverse events

Collected over Adverse event data were collected beginning with the initial inoculation through 6 weeks after administration of the final dose (30 weeks). Non-serious events are listed at a 0% frequency threshold.

Adverse event summary by group
Group	Deaths	Serious	Other
Females, 3 Dose Standard	0/221 (0%)	0/221 (0%)	0/221 (0%)
Females, 2 Dose With Delayed 3rd Dose	0/217 (0%)	0/217 (0%)	0/217 (0%)
Males, 3 Dose Standard	0/165 (0%)	0/165 (0%)	0/165 (0%)
Males, 2 Dose With Delayed 3rd Dose	0/164 (0%)	0/164 (0%)	0/164 (0%)

Baseline characteristics

Age, Continuous
Age, Continuous(Years)	Females, 3 Dose Standard	Females, 2 Dose With Delayed 3rd Dose	Males, 3 Dose Standard	Males, 2 Dose With Delayed 3rd Dose	Total
Mean	21.0 ± 3.41	21.3 ± 3.53	20.82 ± 3.78	20.63 ± 3.85	20.96 ± 3.62

Sex: Female, Male
Sex: Female, Male(Participants)	Females, 3 Dose Standard	Females, 2 Dose With Delayed 3rd Dose	Males, 3 Dose Standard	Males, 2 Dose With Delayed 3rd Dose	Total
Female	221	217	0	0	438
Male	0	0	165	164	329

Ethnicity (NIH/OMB)
Ethnicity (NIH/OMB)(Participants)	Females, 3 Dose Standard	Females, 2 Dose With Delayed 3rd Dose	Males, 3 Dose Standard	Males, 2 Dose With Delayed 3rd Dose	Total
Hispanic or Latino	66	69	46	42	223
Not Hispanic or Latino	155	148	119	122	544
Unknown or Not Reported	0	0	0	0	0

Race (NIH/OMB)
Race (NIH/OMB)(Participants)	Females, 3 Dose Standard	Females, 2 Dose With Delayed 3rd Dose	Males, 3 Dose Standard	Males, 2 Dose With Delayed 3rd Dose	Total
American Indian or Alaska Native	0	0	0	0	0
Asian	18	17	13	28	76
Native Hawaiian or Other Pacific Islander	0	0	1	0	1
Black or African American	38	42	17	21	118
White	165	158	134	115	572
More than one race	0	0	0	0	0
Unknown or Not Reported	0	0	0	0	0

Seropositivity at Baseline
Seropositivity at Baseline(Participants)	Females, 3 Dose Standard	Females, 2 Dose With Delayed 3rd Dose	Males, 3 Dose Standard	Males, 2 Dose With Delayed 3rd Dose	Total
HPV-6	45	50	22	26	143
HPV-11	44	47	21	26	138
HPV-16	60	62	33	34	189
HPV-18	38	50	23	22	133
HPV-31	37	46	20	17	120
HPV-33	24	31	15	12	82
HPV-45	22	30	18	12	82
HPV-52	49	53	33	30	165
HPV-58	33	43	19	16	111

Study locations

1 site

University of Texas Medical Branch
Galveston, Texas 77555, United States

References and documents

Publications

Bergman H, Henschke N, Arevalo-Rodriguez I, Buckley BS, Crosbie EJ, Davies JC, Dwan K, Golder SP, Loke YK, Probyn K, Petkovic J, Villanueva G, Morrison J. Human papillomavirus (HPV) vaccination for the prevention of cervical cancer and other HPV-related diseases: a network meta-analysis. Cochrane Database Syst Rev. 2025 Nov 24;11(11):CD015364. doi: 10.1002/14651858.CD015364.pub2. PubMed 41276263 ↗
Berenson AB, Panicker G, Unger ER, Rupp RE, Kuo YF. Immunogenicity of 2 or 3 Doses of 9vHPV Vaccine in U.S. Female Individuals 15 to 26 Years of Age. NEJM Evid. 2024 Feb;3(2):EVIDoa2300194. doi: 10.1056/EVIDoa2300194. Epub 2024 Jan 23. PubMed 38320488 ↗

Study documents

Protocol and statistical analysis plan · Feb 13, 2025

Documents are hosted by the registry — open the source record to download them.

Updates

Tracking since Sep 25, 2026

No changes since tracking began. The registry record was last updated on Apr 16, 2026, before this site started recording changes on Sep 25, 2026. Its history is on ClinicalTrials.gov ↗

Registry details

Key details

Study ID: NCT03943875
Lead sponsor: The University of Texas Medical Branch, Galveston
Collaborators: Cancer Prevention Research Institute of Texas
Responsible party: Sponsor
First posted: May 9, 2019
Start date: Jun 17, 2019
Primary completion: Jan 13, 2025
Completion: Jan 13, 2025
Results posted: Feb 17, 2026
Last update: Apr 16, 2026

Study contacts

Abbey B Berenson, MD, PhD

principal investigator · University of Texas

Oversight

Data monitoring committee: No
FDA-regulated drug: Yes
FDA-regulated device: No

View the source record on ClinicalTrials.gov ↗

Not currently enrolling

This study is completed, as verified in Apr 2026. You cannot join it, but the record below documents what was studied.

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Discussion

Questions and observations about this study, from anyone following it. Not medical advice, and not a channel to the study team — their contact details are on the registry record.

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Nothing here yet. If you are running this trial, taking part in it, or weighing whether to, this is the place to say so.

Other studies from this sponsor

The University of Texas Medical Branch, Galveston

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