Gardasil Coverage
Gardasil (quadrivalent HPV vaccine) covers four HPV strains: types 6,11,16, and 18 1.
Strain-Specific Protection
The quadrivalent vaccine targets:
- HPV types 16 and 18 (high-risk oncogenic types): These cause approximately 70% of cervical cancers worldwide 1
- HPV types 6 and 11 (low-risk types): These cause approximately 90% of genital warts 2
Clinical Significance by HPV Type
High-risk oncogenic strains (16,18):
- Prevent cervical cancer precursor lesions (CIN 2/3, AIS)
- Prevent vaginal and vulvar cancer precursors
- Prevent anal cancer precursors
- Associated with oropharyngeal cancers 1
Low-risk strains (6,11):
- Prevent genital warts in both males and females
- Prevent recurrent respiratory papillomatosis 1
Important Caveats
Limited coverage: While Gardasil protects against the four most clinically significant HPV types, it does not protect against other high-risk HPV types (31,33,35,39,45,51,52,56,58,59,68,69,73,82) that collectively account for the remaining 30% of cervical cancers 1. This is why cervical cancer screening remains mandatory even after vaccination 1.
Timing matters: The vaccine provides no protection against HPV types with which individuals are already infected at the time of vaccination. However, those infected with one vaccine HPV type will still be protected against the other vaccine types 1.
Note on Gardasil 9
A newer nonavalent vaccine (Gardasil 9) is now available that covers nine HPV types (6,11,16,18,31,33,45,52,58), providing protection against approximately 90% of cervical cancers rather than 70% 3. If the question specifically refers to the original quadrivalent Gardasil formulation, the answer remains the four strains listed above.