Marina, a New York City native, received the first of the three vaccinations against the human papillomavirus (HPV) at age 17—but skipped the final two.

Now she’s infected with this sexually transmitted disease, and much more likely to develop genital warts as well as cervical and several other kinds of cancer.

“If I had known more about HPV, I would have taken all the necessary precautionary steps," she says.

Marina, who asked that we not use her last name, is hardly alone. Many parents and their children underestimate the risks of HPV or fail to take the steps needed to avoid it.  

According to the Food and Drug Administration, the vaccine is 100 percent effective at preventing infections from several serious HPV strains when given in the right doses at the right time.

The Centers for Disease Control and Prevention (CDC) recommends that young adolescents (ages 11 to 14) receive two doses of the HPV vaccine, six months apart. Those who begin the series later, between 15 and 26, will need three doses.

Yet less than half of girls in the U.S. between 13 and 17 and just over a quarter of boys that age had finished the series in 2015, the most recent year for which data is available, according to the CDC.

And a Consumer Reports analysis of vaccination patterns among California primary-care physician groups suggests that even fewer children get the vaccine by age 13, when experts say it’s most effective.

The data used for the analysis—from the Integrated Health Association, a nonprofit that works to improve the quality and reduce the cost of healthcare—shows that in 2015, only 25 percent of girls and 21 percent of boys in the physician groups had been vaccinated by their 13th birthday. By comparison, almost 80 percent of 13-year-olds in those groups received their other childhood vaccines.

Our analysis also found a wide variation in HPV vaccination rates among physician groups, from less than 3 percent to about 50 percent, for both boys and girls.

Why are so few patients getting the shots even though they're covered by most health insurance plans? And why aren’t doctors doing more to make sure that they do?

One factor may be the way doctors talk with parents and their children about the vaccine, says Pamela Phillips, M.D., chief of pediatrics at Cedars-Sinai Medical Group in Los Angeles. In 2015, her practice had one of the highest HPV vaccination rates in the state, with 47 percent of males and 37 percent of females getting all three doses by age 13.

“The language one uses to present a vaccine and the confidence with which a doctor talks about it makes a big difference,” Philips says.

She makes sure to explain what the vaccine is for, how effective it is, and why it’s so important, and even brings her personal experience into the discussion. “I always say that I gave it to my kids when they were 11," she says.

Still, Phillips notes that it’s often hard to convince parents to let their children get vaccinated, in part because of the many myths and misconceptions about HPV. Below are 7 common myths and the truths behind them.

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Myth 1: HPV Is Uncommon and Poses Little Danger

Truth: It’s actually the most common sexually transmitted disease, in males and females, affecting 79 million Americans and many millions more people worldwide. There are an estimated 14 million new cases each year in the U.S. alone, half in people 15 to 24 years old.

It’s true that most people who are infected fight off the virus, and have no signs of it after two years. But during that time, you can still spread it to others. And HPV is a leading cause not only of cervical cancer but also cancers of the penis, anus, throat, mouth, head, and neck.

How can you get HPV

Myth 2: The HPV Vaccine Is Risky

Truth: The side effects of the HPV vaccine are no more serious or frequent than those of other vaccines—which means that it’s quite safe, says Melissa Gilkey, Ph.D., who specializes in adolescent health, cancer prevention, and vaccine research in the department of Population Medicine’s Center for Healthcare Research in Pediatrics at Harvard Medical School.

A 2014 CDC report, which looked at more than 67 million doses of the vaccine given between June 2006 and March 2014, found that only 4 percent were linked to side effects. The most common: dizziness and fainting after injection (which is why you should sit for 15 minutes after getting the shot), local reactions at the injection site, nausea, and headache.

What you should know
about the HPV vaccine

Myth 3: My Child Isn't Sexually Active, So the Vaccine Is Unnecessary

Truth: That’s actually the best time to get immunized against HPV, for several reasons. First, the HPV vaccine works best when it’s given before people are exposed to the virus—which means before they start having sex, says Anna Beavis, M.D., M.P.H., a fellow in gynecologic oncology at Johns Hopkins Hospital in Baltimore and co-author of a comprehensive 2016 review of the vaccine in Frontiers in Oncology.

In fact, getting all three doses at the recommended ages would cut the number of HPV-related cancers by nearly 28,500 a year, according to the American Cancer Society.

In addition, Beavis says, children 10 to 14 years old have a stronger immune response to the vaccine than do older people—so the shot provides better, and likely longer, protection when given then. Finally, teens are less likely to experience side effects than people in their 20s.

Myth 4: My Daughter Gets Regular Pap Smears, so the HPV Vaccine Isn't Needed

Truth: Pap tests have been highly effective at detecting cervical cancer—but don’t prevent cervical cancer like the vaccine does. HPV can also cause other cancers (see Myth 6), which aren’t detected by the Pap test.

In addition, getting vaccinated helps prevent the spread of the HPV virus in the first place.

How the HPV vaccine can help prevent cancer

Myth 5: Getting Vaccinated Will Encourage My Teen to Become Sexually Active

Truth: Many parents worry about this—but research suggests the concern isn’t justified.

A 2012 study by the American Academy of Pediatrics, for example, compared 493 girls who were immunized against HPV with 905 unvaccinated girls. It found no significant differences between the groups in how often the girls received contraceptive counseling or were tested for a sexually transmitted disease, or in pregnancy rates.

In addition, children often become sexually active sooner than their parents might like to think. “The average age in the U.S. for initiation of sexual activity is around 14 to 15 years old,” Beavis says. “Many teens already are sexually active, and getting vaccinated against HPV isn’t going to make that more likely.”

Myth 6: The Vaccine Is Only Really Important for Girls—and I Have a Son

Truth: In addition to cervical cancer, HPV has been linked to genital warts, plus cancers of the penis, anus, throat, mouth, head, and neck—which affect males.

Having boys vaccinated appropriately might prevent about 11,000 cases of HPV-related cancers in U.S males each year. And while men who are infected with HPV may not experience symptoms, they can still infect their partners, so getting vaccinated reduces the spread of the virus to others.

Myth 7: It Will Wear Off by the Time My Youngster Needs It

Truth: Unlike some other shots, there’s no evidence that the protective effect of the HPV vaccine, which was first approved in 2006 for girls and women and in 2009 for boys and men, diminishes with time, Beavis says. That’s why experts say no boosters are needed, at least for now. “Research suggests that it lasts at least eight to 10 years,” Beavis says, and “ongoing studies will likely show that it lasts even longer.”