Can a person with High-grade Squamous Intraepithelial Lesions (HSIL) receive the Human Papillomavirus (HPV) vaccine, such as Gardasil (quadrivalent human papillomavirus vaccine) or Cervarix (bivalent human papillomavirus vaccine)?

HPV Vaccination for Individuals with High-grade Squamous Intraepithelial Lesions (HSIL)

Yes, a person with High-grade Squamous Intraepithelial Lesions (HSIL) can receive the HPV vaccine, but it will only protect against HPV types not already acquired and will not have therapeutic effects on existing infections or lesions. 1

Rationale for Vaccination in Individuals with HSIL

• The HPV vaccine is primarily preventive, not therapeutic, and works by protecting against infection with specific HPV types before exposure occurs 1
• Individuals with HSIL may still benefit from vaccination if they haven't been infected with all vaccine-covered HPV types 1
• The quadrivalent HPV vaccine (Gardasil) protects against HPV types 6,11,16, and 18, while the newer nonavalent vaccine (Gardasil 9) protects against HPV types 6,11,16,18,31,33,45,52, and 58 2
• Even with existing HSIL, vaccination can provide protection against other HPV types included in the vaccine that the person has not yet acquired 1

Important Considerations for Vaccination in HSIL Patients

• The Advisory Committee on Immunization Practices (ACIP) does not contraindicate HPV vaccination for individuals with abnormal Pap tests or known HPV infections 1
• Vaccination will not have any therapeutic effect on existing HPV infections, cervical lesions, or genital warts 1
• With increasing severity of Pap test findings (such as HSIL), the likelihood of infection with HPV 16 or 18 increases, potentially reducing the benefit of vaccination 1
• Cervical cancer screening must continue according to guidelines even after vaccination 1

Vaccination Schedule for Individuals with HSIL

• For individuals aged 15-26 years, a 3-dose schedule is recommended at 0,2, and 6 months 1
• For immunocompromised individuals aged 9-26 years, a 3-dose schedule is also recommended 1
• The FDA has approved Gardasil 9 for use in individuals aged 9-45 years 2

Efficacy Considerations in Previously Infected Individuals

• In clinical trials, the efficacy of the quadrivalent HPV vaccine was 99% for preventing CIN II/III caused by HPV 16 or 18 in women not previously infected with these types 1
• However, efficacy was only 44% in those who had been infected before vaccination 1
• Studies show that vaccination after infection with one HPV type still provides protection against other vaccine HPV types not yet acquired 1

Common Pitfalls and Caveats

• A common misconception is that HPV vaccination is not beneficial after HPV infection or abnormal cytology has been detected 1
• Vaccination should not replace regular cervical cancer screening, as the vaccines do not protect against all oncogenic HPV types 1, 2
• HPV testing should not be used to determine eligibility for vaccination 1
• The vaccine will not eliminate the need for continued screening and appropriate follow-up of abnormal results 1, 2

Conclusion for Clinical Practice

• Individuals with HSIL can receive the HPV vaccine, which may provide protection against HPV types not already acquired 1
• Vaccination should be considered as part of a comprehensive approach that includes appropriate management of the existing HSIL and continued cervical cancer screening 1
• Clear communication about the preventive (not therapeutic) nature of the vaccine is essential to set appropriate expectations 1