Prevention of human papillomavirus infections and associated diseases by vaccination: a new hope for global public health.

Cervarix and Gardasil, 2 human papillomavirus (HPV) vaccines, have been approved and implemented globally in young adolescent women with the hope of reducing the incidence of cervical cancer several decades hence. This program is dependent on the concept of 'immunobridging': antibody titers generated in young adolescents that are the same or higher than generated in HPV-naive 16- to 26-year-old women, the population in which efficacy is proven. Likewise, realizing a decline in cervical cancer from young adolescent female vaccination depends on the duration of vaccine efficacy, and the population coverage reached. While we patiently wait for results from our young adolescent vaccination programs, newly released data indicates that the immunogenicity and efficacy of the vaccines for young adult women with prior HPV exposure is equal or superior to that seen for young adolescents. This same concept of immunobridging supported by limited efficacy data offers the potential to reduce cervical cancer precursors within just a few years in our young sexually active adult women, a population secondary to our young adolescents. The HPV vaccines are not therapeutic. Neither vaccine will inhibit an already HPV-infected basal epithelial cell which continues to transform differentiated epithelial layers into cervical dysplasias. There is a clinical hope, though, already supported by early data, that the vaccines are capable of neutralizing HPV virions in host tissues from both auto-inoculated infections and infections in other organs than the cervix, thereby making it possible for these vaccines to prevent less common HPV-associated cancers of the penis, vagina, vulva, anus, oral cavity and oro-pharynx. Both vaccines have been shown to be generally safe in the phase II and phase III randomized controlled trials over 3-6.4 years. Post-marketing surveillance of Cervarix and Gardasil continues to show that they are safe for most women despite rarely occurring serious events.