HPV Vaccination After Infection: Benefits and Recommendations
HPV vaccination can provide partial benefit even after infection by protecting against HPV types not yet acquired, though it does not treat or clear existing infections. 1, 2
Benefits of Post-Infection Vaccination
- HPV vaccination does not protect against persistent infection, cervical cancer precursor lesions, or genital warts caused by HPV types that a person is already infected with at the time of vaccination 1
- However, individuals already infected with one or more vaccine HPV types would still be protected against disease caused by other vaccine HPV types they have not yet acquired 1, 3
- The majority of sexually active females would derive at least partial benefit from vaccination, even if they have been exposed to some HPV types 1
- Natural immunity from prior HPV infection does not provide complete protection against reactivation or reinfection by the same HPV genotype 1
Evidence for Post-Infection Vaccination Efficacy
- Immunization with the quadrivalent HPV vaccine resulted in 64.9% efficacy in preventing new cervical lesions by any HPV genotype in women who had been treated for cervical lesions 1
- A study of 737 women undergoing cervical conisation showed that the quadrivalent HPV vaccine was associated with a 65% reduction in HPV recurrence at 2 years, regardless of genotype 1
- The post-treatment risk reduction of new lesions following bivalent vaccine immunization in women with surgically treated cervical lesions was 88.2%, regardless of genotype 1
- Long-term follow-up demonstrated protection even in individuals with current or prior HPV infection after approximately 3 years 4
Recommendations for Different Populations
For women with precancerous cervical lesions:
- HPV vaccination is strongly recommended for women undergoing treatment for precancerous cervical lesions 1
- Patients with precancerous cervical lesions who have not yet been treated may also benefit from HPV vaccination 1
- Ideally, the vaccine should be administered early, either at diagnosis or before cervical conisation 1
For the general population:
- Routine vaccination is recommended for females aged 11-12 years, but can be started as early as age 9 1, 2
- Catch-up vaccination is recommended for all persons through age 26 years who are not adequately vaccinated 2
- For sexually active individuals who have not been infected with all HPV vaccine types, vaccination would still provide benefit 1
Important Clinical Considerations
- HPV vaccination does not replace the need for cervical cancer screening; regular screening should continue according to guidelines 2
- No prevaccination testing is recommended before vaccination 2
- The vaccine's effectiveness decreases with older age and likelihood of HPV exposure with increasing number of sex partners 1
- For individuals with HPV-associated oropharyngeal squamous cell carcinoma (OPSCC), there is currently no evidence that HPV vaccination provides benefit after diagnosis 1
Dosing Schedule
- For individuals initiating vaccination before their 15th birthday, a 2-dose schedule is recommended with doses at 0 and 6-12 months 2
- For those initiating vaccination at age 15 years or older, a 3-dose schedule is recommended with doses at 0,1-2, and 6 months 2
- A 3-dose schedule is recommended for individuals with certain immunocompromising conditions, regardless of age at initiation 2
Pitfalls and Caveats
- HPV vaccination is preventive, not therapeutic - it cannot clear existing infections or treat established disease 3
- The benefit of vaccination decreases as the number of prior HPV exposures increases 1
- Vaccination should not be delayed in the hope of clearing an infection, as new infections with other HPV types can still occur 1, 3
- The cost-benefit ratio of vaccination decreases with increasing age, which may limit implementation of routine vaccination beyond the late 20s 5