The HPV quadrivalent vaccine costs$899 and is able to prevent HPV types 6, 11, 16 and 18. The HPV nine-valent vaccine, which adds HPV types 31, 33, 45, 52 and 58 to the quadrivalent vaccine, is able to prevent 90% of cervical cancers caused by HPV and costs$1,299. The HPV vaccine is approved by the U.S. FDA for application to women aged 9-26 years for a total of three intramuscular injections (0, 2 and 6 months.) The HPV vaccine is only effective when administered before HPV infection, and there are many HPV subtypes; even if infected by one subtype, the vaccine remains effective against other HPV subtypes. The American College of Obstetricians and Gynecologists recommends that the HPV vaccine be administered around 11-12 years of age. The duration of immune protection from the vaccine is inconclusive, and the HPV vaccine should be contraindicated during pregnancy.