Prospects and prejudices of human papillomavirus vaccines in India.

Cervical cancer is the most common cancer and a leading cause of cancer deaths among women in developing countries. The disease is caused due to persistent infection of one or more of about 15 high-risk human papillomaviruses (HR-HPVs), most commonly by HPV types 16/18. In India, over 98% of cervical cancer cases harbor HPV infection and HPV 16 is the type exclusively (80-90%) prevalent. Unlike the West, HPV infection is most common in women in their third decade (26-35 years) of sexual activity and invasive cancer also arises much later with a peak at about 45-55 years of age. Recently, two successful prophylactic HPV vaccines, a quadrivalent (HPV16/18/6/11) 'Gardasil' by Merck and a bivalent (HPV16/18) 'Cervarix' by GSK have been developed. Several other approaches including plant-based edible, pentameric capsomere-based intranasal and DNA-based vaccines have also been employed to develop prophylactic vaccines. Also, several therapeutic vaccines either protein/peptide based or DNA based are in clinical trials but are yet to establish their efficacy. Though there are several issues regarding implementation of the already developed vaccines in resource limited countries, efforts are being made to develop cost-effective second-generation vaccines. If cost minimized, HPV related new technologies involved in screening tests and vaccines are expected to reduce incidence of cervical cancer and deaths it causes in women from developing countries.