Two or three doses of human papillomavirus vaccine?

Human papillomavirus (HPV) vaccines have the potential to prevent the considerable morbidity and mortality caused by oncogenic HPV types. In the eight years since the vaccines were first licensed, we have seen remarkable reductions in genital warts, HPV infections, and pre-cancerous cervical lesions in vaccinated populations.1 2 3 4 5 6 7 8 However, achieving high coverage with three doses of vaccine is challenging in many populations, and the cost of the vaccine has kept it out of reach for many countries. In a linked paper (doi:10.1136/bmj.g7584), Jit and colleagues explore, through modelling, the potential cost effectiveness of a two dose HPV vaccination schedule.9

Both the bivalent and quadrivalent HPV vaccines were initially registered for use as three dose courses given over six months, using the model of subunit vaccines for which multiple doses are needed to generate a sufficient immune response. However, HPV vaccines are notably immunogenic, producing very high and durable antibody responses, and the virus-like particle structure of the vaccines, with their repetitive antigen display, may be stimulating immunity that is more akin to the response generated by viral infections or live vaccines.10 …