The human papillomavirus, or HPV, vaccine safeguards 9- to 15-year-olds from infection for at least eight years, scientists report August 18 in Pediatrics. HPV can cause cancer in humans’ reproductive organs. Because most teens have sexual intercourse by 18 years of age, health agencies, including the U.S. Centers for Disease Control and Prevention, consider HPV vaccination in early adolescence crucial for reducing cancer rates. The study marks the longest duration reported so far for the vaccine’s efficacy.