It’s a moment every parent dreads—a phone call from a sobbing child. In Valerie Eipper’s case, her 20-year-old daughter had just found out she had human papillomavirus (HPV), a sexually transmitted infection that can cause cancer. “She was devastated,” says Eipper, 53, a Front Range resident and systems analyst at Oracle. Upon hearing the news, Eipper’s breath caught in her throat. She remembered how their doctor had pushed her to vaccinate her then-15-year-old in 2006, when the HPV vaccine came out, and how Eipper had refused, concerned about the new vaccine’s safety. At the time, her daughter wasn’t sexually active. Now, it was too late.

Eipper was one of a huge number of Colorado parents who are choosing not to inoculate their children against HPV. Despite the fact the vaccine is the first-ever to prevent certain cancers and is considered very safe by the Centers for Disease Control and Prevention (CDC), coverage rates for Colorado teens are an abysmal 38 percent.

That percentage has local doctors concerned. HPV is so common that nearly every sexually active man or woman will contract one of the approximately 40 strains at some point in their lives. And while not all strains cause cancer, each year more than 20,000 HPV-associated cancers occur in women, and about 12,000 are found in men. “In 2011, Colorado was 10 percent lower than the national coverage level for the HPV vaccine—which was already pretty low,” says Dr. Matthew F. Daley, a pediatrician and researcher at the Institute for Health Research at Kaiser Permanente Colorado and the University of Colorado Denver. “The 2012 numbers are better, but at this rate, we’re looking at a missed opportunity to prevent cancer.”

Meanwhile, coverage rates for other vaccines given to adolescents, like Tdap, which prevents diphtheria, tetanus, and whooping cough, are higher—85 percent in Colorado. “The safety risks for the HPV vaccine are no higher than other teenage vaccines, but there’s still a large portion of parents who have concerns about it,” says pediatrician and vaccine researcher Dr. Amanda Dempsey from the University of Colorado Denver. Those worries, says Front Range resident, mother, and registered nurse Marian Mead, have little to do with safety concerns about the relatively new vaccine. “Parents don’t like to talk to their kids about sex,” she says.

Mead is not alone in her belief. If you Google “HPV vaccine,” the so-called morality issue pops up almost immediately. According to health-care providers, the moral dilemma has everything to do with the child’s age. It’s easier for parents to discuss a vaccine for an STD with their 17-year-old than with their middle schooler. Yet the CDC recommends that HPV shots be given at age 11 or 12, before kids begin having sex. “If it helps, parents shouldn’t think of the HPV vaccine as a safeguard from an STD,” Daley says. “Think of it as protection against cancer.”