RecruitingPHASE4INTERVENTIONAL

Persistence of Immune Response Six Years After One Dose of 9vHPV Vaccine Among Male and Female Students

This study is checking how well a single dose of the HPV vaccine (called Gardasil-9) protects young people six years after they got it. In Quebec, Canada, students in Grade 4 (around 9-11 years old) have been receiving just one dose of this vaccine since 2019. Scientists want to understand if this one dose provides lasting protection, especially as these young people get older. Very little is known about the long-term protection of a single HPV vaccine dose, particularly for boys. The study will involve about 300 students (150 girls and 150 boys) who received their single vaccine dose in 2019-2020. They will answer a few health questions and provide a small blood sample to check their immunity.

At a glance

Status

Recruiting

Phase

PHASE4

Sponsor

Canadian Immunization Research Network

Enrolment target

300

Start

23 Sep 2025

Estimated completion

01 Feb 2026

HPV Vaccine

What is this study about?

You might be wondering about a study looking into the HPV vaccine. This research is focused on understanding how well a single dose of the HPV vaccine, called Gardasil-9, protects young people over a longer period. In Quebec, Canada, school children in Grade 4 (which is usually for 9-11 year olds) have been offered just one dose of this vaccine since the 2019-2020 school year. This is a bit different from how it used to be. Experts in Canada and around the world now suggest that one dose might be enough for many young people.

The main aim of this study is to see if the protection provided by that single vaccine dose is still strong six years later. The HPV vaccine helps protect against a common virus that can cause certain cancers. It’s really important to know if one dose offers lasting protection, especially as young people start becoming more active and might be exposed to the virus. Scientists want to understand this better, particularly because there isn't much information available about the long-term effects of a single dose, especially for boys.

Researchers will work with about 300 young people – half girls and half boys – who got their single HPV vaccine dose when they were in Grade 4 in 2019-2020. This study is taking place at a research centre in Quebec City, Canada. The results will help doctors and health organisations make the best recommendations for HPV vaccination programmes in the future.

Key takeaways

This study evaluates how long a single dose of the HPV vaccine protects young people.
It aims to understand if one dose provides long-term immunity, especially for boys.
Participants will have had one HPV vaccine dose between ages 9-11 in 2019-2020.
Taking part involves answering health questions and giving a small blood sample.
Results will help inform future HPV vaccination guidelines globally.

Who may be eligible?

This study is looking for young people who meet specific criteria. You might be able to take part if you are between 15 and 17 years old right now.

To be eligible, you must have received only one dose of the Gardasil-9 HPV vaccine when you were between 9 and 11 years old, specifically during the 2019-2020 school year. It’s important that you haven't had any other HPV vaccine doses.

There are also a few things that would mean you can't take part. If you have a weakened immune system, either now or when you had your vaccine, you wouldn't be able to join the study. Also, you need to be able to understand and agree (consent) to be part of the study.

Could this study suit you?

Answer these quick questions to see if you may be eligible. This is a guide only — the research team makes the final call.

Are you currently between 15 and 17 years old?
Did you receive only one dose of the Gardasil-9 HPV vaccine?
Did you get this single dose between ages 9 and 11, during the 2019-2020 school year?
Do you not have a weakened immune system?
Are you able to understand and agree to participate in the study?

Answer every question to see your result.

What does participation involve?

If you decide to take part in this study, the first step will be to answer a few questions about your health to make sure you're eligible. If you are, and you agree to participate, you'll be asked to provide a small blood sample. This sample will be about 10 ml, which is less than one tablespoon. This blood sample is used to check your levels of protection against HPV. The study will be conducted at the CHU de Québec-Université Laval research center in Quebec City.

Potential risks and benefits

Taking part in this study helps doctors and scientists understand if a single dose of the HPV vaccine offers long-term protection, which could improve vaccination programmes for young people in the future. The main procedure involves a blood test, which carries a very small risk of minor discomfort, bruising, or feeling a little dizzy afterwards. You are free to change your mind and withdraw from the study at any time without giving a reason, and this will not affect any healthcare you receive.

Locations (1)

Centre de recherche du CHU de Québec-Université Laval
Verified postcode
Québec, Canada· Recruiting

Common questions

What is the HPV vaccine?

The HPV vaccine helps protect against Human Papillomavirus (HPV), a common virus that can lead to certain cancers, like cervical cancer, and other health problems.

Why is this study important?

This study is important because it will help us understand if one dose of the HPV vaccine provides long-lasting protection, especially for young people as they get older.

Will I get any medicine or new treatment in this study?

No, this study is about checking the protection from a vaccine you’ve already had. You won't receive any new medication or treatment as part of this research.

How much blood will be taken?

A very small amount of blood will be taken, about 10 ml, which is less than one tablespoon.

Where is the study taking place?

The study is being conducted at the CHU de Québec-Université Laval research center in Quebec City, Canada.

How to find out more

Chantal Sauvageau, MD

chantal.sauvageau@inspq.qc.ca 418650-5115 Official trial record

Always speak to your GP or specialist before deciding to take part in a study.