Researchers have found that one dose of the human papillomavirus (HPV) vaccine could be enough to provide significant protection against cervical cancer. According to the World Health Organization (WHO), cervical cancer is the fourth most common type of cancer in women, with many cases being preventable through the HPV vaccine. The vaccine is available in two or three shots, given to individuals as young as nine years old, but most countries have a low vaccination rate, with WHO hoping to get 90% of girls vaccinated by the age of 15 by 2030.
The introduction of the vaccine in the US in 2006 has resulted in a significant reduction in cervical cancer cases and deaths, with incidence rates among women aged 20 to 24 falling by 65% from 2012 to 2019. The CDC recommends that girls and boys be vaccinated between the ages of 11 and 12. While a two or three-dose schedule is currently recommended, one shot would provide enough protection, based on the latest science, according to the WHO’s Strategic Advisory Group of Experts on Immunization. Currently, coverage is just 13% worldwide.
The single dose would be preferable in terms of logistics and cost-saving for many countries and, based on recent studies, is equally as effective as a multi-dose regime. A controlled, randomized, double-blind trial by the Gates Foundation, involving 2,275 young women in Kenya, found that a single dose has an efficacy rate of 97.5% after a year and a half, comparable to a multi-dose regime after 24 or 30 months. The WHO has recommended facilitating access to the HPV vaccine by offering a single dose, especially in areas where resources are limited.
However, some experts believe that there needs to be longer-term studies to guarantee lifetime protection against all strains of HPV. Others have cautioned that HPV can result in other cancers, such as those of the anus, throat, vulva, and penis, and that the vaccine should be extended beyond the "primary targets" of girls and young women to include boys and older females.