Long term protection against cervical infection with the human papillomavirus: review of currently available vaccines.

Two vaccines against HPV are commercially available: an HPV-16/18 (bivalent) and an HPV-6/11/16/18 (quadrivalent) vaccine. Vaccination programs have been and will be implemented before the full duration of protection is known. Whether booster doses will be required is also unknown at this time. Meanwhile, predictions rely upon phase III studies and mathematical modelling. In a head to head study, the bivalent vaccine induced a higher, more sustained immune response than the quadrivalent vaccine. Immunogenicity of the bivalent vaccine against HPV-16 and HPV-18 has been demonstrated up to 8.4 years. For the quadrivalent vaccine, immunogenicity data up to 5 years show that the immune response against HPV-18 wanes after approximately 4 years. Efficacy against infection and cervical lesions associated with HPV-16/18 has been shown up to 8.4 and 5 years with the bivalent and quadrivalent vaccine, respectively. Cross-protection against non-vaccine types appears stronger with the bivalent vaccine. However, both vaccines may provide sufficient immunogenicity to confer long-term protection. Ongoing monitoring is essential.