Q. I know it's recommended that young girls get vaccinated against HPV, since this virus can cause cervical cancer. What about boys? At one time I read it was not recommended for them, but recently I heard that this had changed. Has it changed, and why?
A. You're right. The CDC's Advisory Committee on Immunization Practices has recently recommended that boys also get the HPV vaccine.
HPV (human papillomavirus) causes genital warts. In women, some strains of the virus cause cancer of the cervix. The cervix is a part of a woman's uterus, the opening into the uterus from the vagina. Vaccines for HPV have been shown to reduce a woman's later risk of getting cervical cancer. The discovery that HPV causes cervical cancer was a landmark discovery that was honored with the Nobel Prize.
So it's clear why the HPV vaccine is recommended for girls. But why is it recommended for boys? HPV can also cause cancers of the anus, penis, vagina, mouth and throat. This makes it a problem for both men and women. In fact, in the U.S., 7,000 men each year get cancers caused by HPV.
When it was first approved in 2006, the first vaccine against HPV -- Gardasil -- was for use only in girls and young women. Although it also was approved for boys in 2009, at that time it wasn't recommended that all boys also be vaccinated. But the recent ACIP recommendations are a stronger push. They actively recommend that boys should be vaccinated at 11 or 12. Why?
Obviously, males can't get cervical cancer. But if they are infected with the virus, they can spread it to women through sexual activity. So vaccinating boys and young men against the virus will help prevent its transmission to women. It will also help prevent some of the 7,000 HPV-related cancers that occur in men each year.
The CDC hopes that the recommendation will help make up for the fact that fewer girls than it had hoped have been vaccinated. So far, only about one-third of girls eligible for vaccination against HPV have gotten all three necessary shots.
The more people who are vaccinated against a virus, the less that virus can circulate in the community. Vaccinating boys, too, helps our health as a group. This is sometimes called "herd immunity."
Some parents take issue with the idea of vaccinating young children against a disease that is transmitted sexually. This may be part of the reason not as many girls as expected have been vaccinated. Making the HPV vaccine part of routine vaccines for all children may help remove some of the stigma. Vaccinating kids before they might become sexually active makes sense.
I know some people ask the question: Why should you vaccinate a child against a sexually transmitted disease he or she may never get? But there is another question I'd ask these people to consider: Why wouldn't you vaccinate your child to protect them against a cancer that they could get? In my view, it's a miracle that we can vaccinate against a life-threatening cancer. The arguments in favor of routinely giving the HPV vaccine to kids are very strong.
• Dr. Komaroff is a physician and professor at Harvard Medical School. Go to his website to send questions and get additional information: www.AskDoctorK.com.