Introduction to the nine-valent vaccine The nine-valent vaccine is a vaccine that prevents cancer caused by human papillomavirus (HPV) infection. It protects against HPV-related cancers and other diseases, including cervical, anal, and head and neck cancers. Currently, the only FDA-approved nine-valent vaccine brand on the market is Merck’s Gardasil9. The 9-valent vaccine has been recommended as a routine vaccine for adolescents and young adults in the United States and other countries. The effectiveness and safety of the nine-valent vaccine Since its launch, the nine-valent vaccine has been proven to be very effective and safe.