Adding Male Single Dose HPV Vaccination to Female HPV Vaccination in Tanzania (Add-Vacc)

September 2, 2026 updated by: London School of Hygiene and Tropical Medicine
Add-Vacc is an unblinded cluster-randomised trial (CRT) with two arms: (i) the national HPV vaccination programme (girls aged ~14 years, control arm) and (ii) the national programme plus single-dose male HPV vaccination given to a multi-year cohort of boys (intervention arm). The CRT will be conducted in 26 communities/clusters (13 per arm) in northern Tanzania. Boys aged 14 to 18 years in the intervention arm will receive one dose of the 4-valent HPV vaccine (Gardasil®) that protects against HPV 6, 11, 16, and 18. Population genital HPV prevalence in 18 to 21-year-olds will be compared between intervention clusters (female and male vaccination) and control clusters (female vaccination only) at 3 years after the intervention. Blood sampling for immune responses and adverse event data collection will be performed in a subset of 200 male subjects in selected intervention clusters.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
10400

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Phase 4

Contacts and Locations

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

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Locations

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

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

14 years to 18 years (Child, Adult)

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

  • Parents and adult male participants (aged 18 years) must sign an ICF and male participants aged less than 18 years must sign an informed assent form (IAF), indicating that they understand the purpose of and procedures required for the study and are willing to participate in the study and to receive HPV vaccination. If the parent or participant cannot read or write, the procedures must be explained and informed consent/assent must be witnessed by a literate third party who is not involved in the conduct of the study.
  • Participants must have been born male, and must be aged 14 to 18 years inclusive at time of vaccination.
  • Participants must be living in an intervention community (cluster).
  • Participants must be willing and able to comply with the protocol requirements.
  • Participants must agree to avoid all non-trial immunisations in the 14 days following vaccination with the trial vaccine, other than emergency vaccinations such as post-exposure rabies or tetanus vaccinations.
  • Participants must be healthy as determined by a medical history. A physical examination will be conducted if necessary according to the clinician's judgement.

Exclusion Criteria:

Boys will be excluded from HPV vaccination if:

  • They have previously been vaccinated against HPV.
  • They have a history of allergy or anaphylaxis to one or more of the HPV vaccine components, to yeast or to latex.
  • They are enrolled in another vaccine research study that specifically specifies that they must not participate in a study of another vaccine
  • They have been diagnosed with a chronic condition (except HIV, as per the comment above), such as an autoimmune condition, sickle cell disease, degenerative disease, neurologic or genetic disease, among others;
  • There are significant conditions or clinically significant findings for which, in the opinion of the investigator, participation would not be in the best interest of the participant (e.g., it would compromise their safety or well-being).

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

  • Primary Purpose: Prevention
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Single

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: Male vaccination + national HPV vaccination programme
Single dose of the 4-valent HPV vaccine (Gardasil®; Merck & Co.) offered to all eligible boys aged 14 to 18 years in the 13 intervention communities. Girls aged 14 years are offered 2 doses of Gardasil® through the Tanzanian national HPV vaccine programme
Biological: Gardasil® HPV vaccine
Single dose 4-valent HPV vaccine in males. Gardasil®, manufactured by MSD, consists of a licensed prophylactic virus-like particle (VLP) vaccine that protects against 4 HPV genotypes (HPV 6, 11, 16, 18).
Other Names:
  • 4-valent HPV vaccine
Active Comparator: National HPV vaccination programme only
Girls aged 14 years are offered 2 doses of Gardasil® through the Tanzanian national HPV vaccine programme
Biological: Gardasil® HPV vaccine
Single dose 4-valent HPV vaccine in males. Gardasil®, manufactured by MSD, consists of a licensed prophylactic virus-like particle (VLP) vaccine that protects against 4 HPV genotypes (HPV 6, 11, 16, 18).
Other Names:
  • 4-valent HPV vaccine

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Impact of adding single-dose male HPV vaccination to the national HPV vaccination programme in girls on population 4-valent HPV genotype prevalence in 18 to 21-year-old females and males
Time Frame: Month 36
Prevalence of 4-valent vaccine HPV genotype DNA (HPV 6, 11, 16 or 18) in males and females aged 18 to 21 years in intervention clusters and control clusters 36 months post-male vaccination
Month 36

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Immunogenicity and safety of single dose 4-valent HPV vaccination in boys
Time Frame: Month 12, 24 and 36
Proportion seroconverting to, and geometric mean antibody titres (GMTs) for, HPV vaccine genotypes, and safety and tolerability (local and systemic adverse events), measured in a subset of 200 vaccinated boys
Month 12, 24 and 36
Impact of female-only vaccination through the national vaccination programme on population HPV prevalence in 18 to 21-year-old males and females
Time Frame: Month 36
The proportion of females, and of males, aged 18 to 21 years in the control arm with detectable genital 4-valent HPV vaccine genotype DNA at baseline and at M36.
Month 36
Uptake of dose 1 and coverage of dose 2 in eligible target groups for the national HPV vaccination programme;
Time Frame: Month 36
The proportion of females aged 16 years who received 1 dose of HPV vaccine (uptake) and who complete 2 doses (coverage) by arm at baseline and M36
Month 36
Acceptability of a gender-neutral approach to HPV vaccination
Time Frame: Month 24
Self-reported acceptability of and barriers to receiving male vaccination by community members and to delivering male HPV vaccination by health care workers (HCW)
Month 24
Cost-effectiveness of adding a multi-year single dose male HPV vaccination strategy to the national female HPV vaccination programme
Time Frame: Month 36
Incremental cost-effectiveness ratio for single dose male vaccination plus existing female vaccination programme compared to female vaccination only
Month 36

Collaborators and Investigators

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

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
London School of Hygiene and Tropical Medicine

Collaborators

Collaborators

An organization other than the sponsor that provides support for a clinical study. This support may include activities related to funding, design, implementation, data analysis, or reporting.
University of Cambridge
Mwanza Intervention Trials Unit, National Institute for Medical Research
York Biomedical Research Institute, Hull York Medical School, University of York
Cancer Epidemiology Research Programme Institut Català d' Oncologia
Karolinska Institute Department of Laboratory Medicine

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

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)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
August 1, 2022

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
December 1, 2026

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
December 1, 2026

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
June 28, 2021

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
June 28, 2021

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
July 7, 2021

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
September 8, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
September 2, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
August 1, 2026

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • MITU-003

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

UNDECIDED

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

Yes

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

Yes

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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