Dr. Donald Brown inoculated Kelly Kent with the HPV vaccine in his Chicago office in the summer of 2006 — not long after the first version of the vaccine reached the market. Charles Rex Arbogast/AP hide caption

itoggle caption Charles Rex Arbogast/AP

Amy Myers talks with her son Kamron, 18, in the backyard of their home in Boise, Idaho. She has found raising a teenager to be extremely stressful. Kyle Green for NPR hide caption

itoggle caption Kyle Green for NPR

A worker cleans the home of a hoarder in Las Vegas. Teens may not have the time to accumulate this much stuff, but they still have symptoms. AP/City of Las Vegas via Las Vegas Review-Journal hide caption

itoggle caption AP/City of Las Vegas via Las Vegas Review-Journal

Singer Ke$ha performs during the iHeartRadio Music Festival at the MGM Grand Garden Arena in Las Vegas in September. Ethan Miller/Getty Images hide caption

itoggle caption Ethan Miller/Getty Images

High school students whose friends posted photos of drinking and smoking were about 20 percent more likely to become drinkers or smokers themselves. iStockphoto hide caption

itoggle caption iStockphoto