The BaTTle for accepTance of hpV Vaccine

Human Papillomavirus (HPV) is the most common sexually transmitted disease on this planet, and is an oncogenic virus associated with a variety of potentially deadly cancers. And yet, though safe and highly effective vaccines for HPV have been developed over the past decade and have been recommended by many professional organizations, utilization of these potentially life-saving vaccines has been blunted by a storm of controversy. This paper summarizes the science behind the HPV vaccines, and outlines the nature of those controversies. DISEASE ASSOcIATED WITH HUMAN PAPILLOMAVIRUS HPV is the most common sexually transmitted infection worldwide. The risk of acquisition begins to rise with the onset of sexual activity, and the prevalence of infection, at least in Western countries, peaks between 15 and 25 years of age. The CDC (Centers for Disease Control and Prevention) estimates that over 80% of sexually active women will be infected with HPV by the age of 50 years. 1 The majority (70%) of HPV infections are transient and asymptomatic, with complete clearing of the virus within the first year of infection. Less commonly, infection with HPV can become chronic and persistent, and it is these infections that serve as a major vehicle of transmission. More importantly, the specific genotype of HPV that causes infection predicts its clinical manifestations. Human Papillomavirus (HPV) is a non-enveloped double-stranded DNA virus that demonstrates a species and tissue tropism for human epithelial cells. The virus contains a circular genome with 8 major gene elements that encode two major structural proteins, L1 and L2. There are over 40 HPV genotypes that are capable of infecting epithelial cells in the anogenital tract in both males and females. HPV6 and HPV11 together cause about 90% of all anogenital warts (condylomata acuminata), and are also associated with the less common syndrome of Recurrent Respiratory Papillomatosis. But the most dangerous consequence of chronic HPV infection is the association of the oncogenic HPV genotypes with cancerous and pre-cancerous lesions. Cervical cancer is the third most common female cancer worldwide. HPV16 and 18 cause about 70% of these neoplasms, and are responsible for about half of precancerous lesions (cervical intraepithelial neoplasia grades 2 or 3). In addition, these same two genotypes account for 40% of vulvar and 70% of vaginal cancers. HPV16 and 18 are also responsible for 70% of anal cancers, with other HPV genotypes accounting for an additional 18%. In addition, 40% of penile cancers are associated with HPV16 and HPV18. In HIV-positive men who have sex with men (MSM), rates of HPV-associated anal cancers are twice that of HIV-negative MSM. Oropharyngeal squamous cell carcinomas caused by HPV are on the rise in the United States; even while non-HPV associated cancers are declining. HPV plays a causative role in carcinomas of the tongue, tonsils, and larynx. HPV16 is the most commonly associated genotype, with HPV-18, 31, and 33 also playing an oncogenic role.