Present status of human papillomavirus vaccine development and implementation.

Oncogenic human papillomavirus (HPV) infection is the cause of nearly all cervical cancers and a proportion of other anogenital and oropharyngeal cancers. A bivalent vaccine containing HPV 16 and 18 and a quadrivalent vaccine containing HPV 6, 11, 16, and 18 antigens are in use in vaccination programmes around the world. In clinical trials, three vaccine doses provided 90-100% protection against cervical infection and pre-cancer related to HPV 16 and 18 in women aged 15-26 years who were not infected at vaccination. Partial cross-protection against other HPV types has been reported but its duration is unknown. The vaccines were also efficacious at the prevention of HPV 16 and 18 infections at other anatomical sites in both sexes. Immunobridging studies allowed licensing of the vaccines for use starting at age 9 years for both sexes. Two-dose schedules elicit high antibody concentrations, leading to the recommendation of two-dose schedules for girls aged 9-14 years. Pre-licensure and post-licensure studies have provided data supporting vaccine safety. In 2014, a nonavalent vaccine containing HPV 6, 11, 16, 18, 31, 33, 45, 52, and 58 antigens was licensed by the US Food and Drug Administration. HPV vaccination was first introduced in high-income countries owing to vaccine cost, logistic challenges, and competing health priorities. Since 2011, vaccine prices have lowered, allowing the introduction of the vaccine in some middle-income countries. Funding of the vaccine by the GAVI Alliance in 2012 led to demonstration projects in some low-income countries. By 2014, more than 57 countries had included the HPV vaccine in their national health programmes. Data from several countries have shown the effect of vaccination on HPV infection and associated disease, and provided evidence of herd immunity. Expansion of programmes to countries with the highest burden of disease is beginning, but further efforts are needed to realise the potential of HPV vaccines.