Human papillomavirus (HPV) is one of the most common sexually transmitted infections, and causes about 31,500 cancers in the United States each year. It also has a vaccine–but many Americans aren’t being vaccinated. The HPV vaccine is already underutilized in the United States, and a new study by researchers at the University of North Carolina found that HPV vaccine follow-through is declining over time. The vaccine, which is highly effective at preventing the development of abnormal cells that can progress to cervical cancer, is delivered in a series of doses. The Centers for Disease Control and Prevention (CDC) recommends that all children ages 11-12 should get two doses of the vaccine six to twelve months apart; adolescents older than 14 should get three shots over four months. Yet the survey of more than a million privately-insured Americans showed that vaccine follow-through declined from 2006 to 2014. The decrease was especially prominent among female patients, from 67% in 2006 to 38% in 2014, but was also present in male patients, from 36% in 2011 to 33% in 2014. While such low follow-through for this effective and important vaccine is concerning, other studies have shown that solutions as simple as a physician’s office sending parents a reminder can greatly increase vaccine follow-through.