Ask Dr. K: Human papillomavirus vaccine has proven benefits

Human papillomavirus (HPV) is the main cause of cervical cancer and genital warts. The linkage of this virus to cancer, and the ability of a vaccine against the virus to reduce the risk of cancer, are solidly established. So much so, in fact, that the discovery of HPV’s connection to cervical cancer was honored with the Nobel Prize.

There are two different forms of the HPV vaccine, Cervarix and Gardasil. Both are safe and effective. The Cervarix vaccine protects against two HPV types, which cause 70 percent of cervical cancers. The Gardasil vaccine protects against these two types as well as two others, which cause 90 percent of genital warts. Gardasil also has been shown to protect against cancers of the vulva, vagina and anus.

Vaccination is recommended for girls aged 11 to 12 years. But it may be given as early as age 9. The vaccine is also recommended for females 13 to 26 who did not get the vaccine earlier. The vaccine is given as three injections over a six-month period. (Vaccination with Gardasil is also recommended for boys ages 11 or 12, to prevent anal cancer and genital warts.)

Based on conversations I’ve had with my pediatrician colleagues, I’d guess your concerns have to do either with either safety or sexual behavior.

Let’s start with safety. Side effects are possible from any medical treatment, including vaccines. But extensive studies have shown that the HPV vaccine is safe for the vast majority of people.

You may also worry that getting the vaccine will give your daughter the green light to have sex. I’m not aware of any evidence that kids given this vaccine are more likely to have sex as teens than kids who aren’t given the vaccine.

This vaccine is about cancer, not sex. The idea is to give the vaccine well before any sexual activity — and exposure to HPV — begins.

The HPV vaccine has already had a big impact. A study published in 2013 showed that since doctors began to routinely give the HPV vaccine in 2006, the occurrence of the cancer-causing HPV strains covered by the vaccine has dropped by 56 percent in girls ages 14 to 19 years.

Remember, though, that the vaccine does not protect against all types of HPV. It is not an absolute guarantee against cervical cancer. As your daughter gets older, she still should get screened for cervical cancer even if she has the HPV vaccine.

The bottom line is that a series of three shots will protect your daughter from a form of cancer that can cause premature death. That’s a gift any parent would want to give his or her child.

Dr. Komaroff is a physician and professor at Harvard Medical School.

To send questions, go to AskDoctorK.com, or write: Ask Doctor K, 10 Shattuck St., Second Floor, Boston, MA 02115.