human papillomavirus 9-valent vaccine
Gardasil 9 is Merck's nine-valent HPV vaccine. It presents virus-like particles from nine human papillomavirus types to the immune system, preventing the HPV infections that can cause cervical, anal and oropharyngeal cancers and genital warts.
This page is based on the FDA-approved Gardasil 9 label and the Health Canada product record; the mechanism is explained in plain language, and analogies are used only where they stay accurate.
How it works
Explains what the medicine does in the body, not dosing, side effects, or safety.
An analogy
The vaccine shows the immune system nine copies of HPV's outer coat - non-infectious shells that look like the virus but are not it. Security forces photograph each shell and build tailored defences. Later, if a real virus of any covered type arrives, the immune system is ready to respond.
In simple terms
Gardasil 9 contains virus-like particles made from the outer (L1) protein of nine HPV types. They are non-infectious - they are virus shells, not the virus. After vaccination, the immune system makes antibodies against each type. These humoral immune responses are thought to mediate protection against the diseases the covered types cause, although the exact mechanism of protection is not known.
In depth
Gardasil 9 is a non-infectious recombinant 9-valent vaccine prepared from the purified virus-like particles (VLPs) of the major capsid (L1) protein of HPV Types 6, 11, 16, 18, 31, 33, 45, 52, and 58; the L1 proteins are produced in recombinant Saccharomyces cerevisiae and self-assembled into VLPs, and the purified VLPs are adsorbed on preformed aluminum-containing adjuvant (Amorphous Aluminum Hydroxyphosphate Sulfate, AAHS). Vaccination induces antibodies against neutralizing epitopes for each HPV type. GARDASIL 9 is not a treatment for existing lesions or cancers and has not been shown to protect against HPV types to which a person has previously been exposed.
See it in motion
A schematic animation of the mechanism — simplified for clarity, not drawn to scale.
Security forces photograph each shell and build tailored defences.
- The vaccine shows the immune system nine copies of HPV's outer coat - non-infectious shells that look like the virus but are not it.
- Gardasil 9 contains virus-like particles made from the outer (L1) protein of nine HPV types.
- After vaccination, the immune system makes antibodies against each type.
- These humoral immune responses are thought to mediate protection against the diseases the covered types cause.
Target: HPV L1 major capsid protein (types 6, 11, 16, 18, 31, 33, 45, 52, 58)
The major capsid (L1) protein of human papillomavirus, self-assembled into virus-like particles; vaccination induces type-specific antibodies, and efficacy against the covered diseases is thought to be mediated by humoral immune responses, although the exact mechanism of protection is unknown. Each vaccine type covers a different HPV type.
Approved uses
Approved uses differ by country and change over time. Always follow your local prescribing information.
Approved uses in United States
FDA- In girls and women 9 through 45 years of age, prevention of cervical, vulvar, vaginal, anal, oropharyngeal and other head and neck cancers caused by HPV types 16, 18, 31, 33, 45, 52 and 58, genital warts caused by HPV types 6 and 11, and precancerous or dysplastic lesions caused by the covered types
- In boys and men 9 through 45 years of age, prevention of anal, oropharyngeal and other head and neck cancers caused by HPV types 16, 18, 31, 33, 45, 52 and 58, genital warts caused by HPV types 6 and 11, and precancerous or dysplastic lesions caused by the covered types
Official sources
The statements on this page trace back to these records.
- DailyMed: Gardasil 9 label
DailyMed, U.S. National Library of Medicine
This page explains how the medicine works — it isn’t the patient leaflet. For anything that applies to you, read the leaflet that came with your medicine or ask your pharmacist.
MedUnfold provides educational content and is not medical advice. Always follow your local prescribing information and healthcare professional.