A study published in this month’s Pediatrics adds to the growing body of evidence showing the HPV vaccine is working to prevent cervical cancer and other health issues that can be caused by the human papillomavirus (HPV).
The study followed high school girls in Canada and found that those who had received the vaccine were much less likely to be diagnosed with genital warts or cervical dysplasia than their unvaccinated peers. These results show that the protective effects of the vaccine kick in quickly and confirm the importance of having young people vaccinated at an early age.
HPV is a highly contagious sexually transmitted disease (STD) that is spread from infected skin to uninfected skin. About 79 million Americans are infected with HPV, and about 14 million people become newly infected each year. The majority of HPV cases are cleared by the body without ever causing symptoms or health problems.
Some strains of the virus, however, can cause genital warts, cervical cancer, and cancers of the penis, anus, head, neck, and throat. Approximately 12,000 women in the United States are diagnosed with cervical cancer each year, and about 4,000 die.
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Condoms can prevent HPV transmission, but only if the infected skin is in an area covered by the condom. If it’s on an area outside of the condom, such as a man’s scrotum, condoms cannot help reduce transmission.
A vaccine has been available to prevent HPV transmission since 2006. Gardasil, that vaccine, protected against four stains of the virus—the two that account for 70 percent of cervical cancers and the two that account for 90 percent of genital warts.
A newly approved version of Gardasil now protects against nine strains of the virus and has the potential to prevent 90 percent of cases of all cervical, vulvar, vaginal, and anal cancer, as Rewire has reported. A second vaccine, called Cervarix, was approved in 2009 but only protects against the two strains that cause most cervical cancer.
The vaccine is given as a series of three shots and is approved for young people—both men and women—between the ages of 9 and 26. The Centers for Disease Control and Prevention (CDC) recommends that HPV vaccines become part of the routine vaccinations for girls who are 11 or 12 years old because in order to ensure that it works, it has to be given before they become sexually active.
Though not recommended as part of the routine vaccinations for boys, health-care providers suggest that they receive the vaccine at the same age.
There have been studies that suggest that the introduction of these vaccines has had a dramatic impact. A 2013 study conducted by the CDC, for example, found that the proportion of girls infected with the four strains covered by the original Gardasil vaccine dropped among all girls (vaccinated or not) from about 12 percent before the vaccine was available to 5 percent, a drop of 56 percent.
When researchers looked at those girls who had been vaccinated, the decrease was even higher, at 88 percent.
That study looked at infections rates rather than cervical cancer rates because cervical cancer grows very slowly. The median age of cervical cancer diagnosis is 48 and even higher for other HPV-related cancers, which means it may be many years before the first generation of young women who received the vaccine would have been facing cancer diagnoses.
The new study adds to the expectation that rates of cervical cancer will come down. It followed more than 26,000 teen girls in Ontario, Canada and found that those who had received all three doses of Gardasil (the original 4-strain version) were 44 percent less likely to be diagnosed with cervical dysplasia and 43 percent less likely to be diagnosed with genital warts during their high school years than their unvaccinated peers.
Genital warts are small painless bumps that can appear on the penis, vulva, vagina, cervix, or anus, as well as in the mouth or throat. They may go away on their own or they may need to be removed by a health care provider. Cervical dysplasia is one name for abnormal changes to the cells on the surface of the cervix considered pre-cancerous and usually detected through a pap test.
These changes put women at a higher risk of cervical cancer, but there are treatments available that can prevent them from becoming cancer.
Linda Levesque, one of the senior authors of the newly published study, explained that cervical dysplasia is “not yet cancer, but over time, if it’s left untreated and unchecked runs the risk of becoming cancer later in a girl’s life.” She told HealthDay News:
“I don’t think we were surprised the vaccine works. … What I was surprised by was the magnitude of benefits in such a young age group. I expected we would see some reductions. I didn’t think they would be so large and of such significance.”
The findings suggest that the CDC and other health agencies are right to recommend that the vaccine be given to young women before their sexual debut.
Some parents have objected to vaccinating kids for an STD at the age of 11, arguing that it is too young to even discuss sexual behavior. The authors disagree. Lead author Leah Smith told HealthDay News:
“Cervical dysplasia and genital warts can happen as soon as a girl becomes sexually active, more or less. … Some parents have been delaying vaccination for their daughters until they’re older, because they don’t think they are sexually active. These results show this age group is sexually active and they are at risk. The vaccine really needs to be given before the girls are at risk.”
HPV vaccination rates in the United States are lower than those for other vaccines. The CDC estimated that if girls 13 to 17 had received one dose of the vaccine when they received the other recommended vaccinations, nine in ten young women would have gotten at least one dose. Instead, data shows that 57 percent of girls between the ages of 13 and 17 had received even one dose, and 38 percent got all three.
Some of this may be the result of an overall distrust of vaccines in the United States, but much of it likely stems from the misplaced fear that vaccinating young women against an STD will give them license to become promiscuous. There is now a plethora of research that show this is not the case, as Rewire has reported.
The authors of the new study emphasized that parents who believe there’s no harm in delaying or skipping the vaccine are putting their daughters’ health at risk.