The number of adult women who contract human papillomavirus (HPV) is going down, probably due to the use of the HPV vaccine. Even unvaccinated women may be benefitting from the decline.
According to a study led by Abbey Berenson, MD, PhD, researchers believe that the use of the HPV vaccine has created "herd immunity" among women, which provides some protection to those women who don't get the vaccine.
"We observed almost a 50% decline in vaccine-type HPV among unvaccinated 18- to 26-year-old women between 2009-2010 and 2013-2014 (19.5-9.7%)," the authors wrote. The study was published in the October issue of Obstetrics & Gynecology. "Because this age group was the only subgroup to demonstrate a significant change in HPV prevalence and this group had the highest vaccination rate, HPV vaccination is likely the cause of the decline," they stated.
Using data from three cycles of the National Health and Nutrition Examination survey, the study examined the prevalence of HPV among women who were between the ages of 18 and 59 years old. Overall, the researchers found that from 2009-2010 to 2013-2014, the prevalence of vaccine-type HPV decreased among all women in the study (prevalence ratio 0.68, 95% CI, 0.47-0.99).
However, when they examined the data further and divided the women into four different age groups, they discovered that decrease was only significant among the women 18-26 years old. This age group saw a reduction in the prevalence of high-risk vaccine-type HPV from 13.1% in the 2009-2010 data to 5.0% in 2013-2014.
Women in this age group were also the group with the highest vaccination level at 44.1%.
Unvaccinated women 18-26 years old also saw a significant decline in vaccine-type HPV from 2009-2010 to 2013-2014, with a prevalence ratio of 0.44.
"While vaccinated women have already had low levels of HPV infections for several years, we are now seeing a reduction in infections among women who have not received the vaccine," Berenson told Drugs.com.
According to the CDC, HPV is said to cause 30,700 cancers each year in men and women. The vaccine may prevent approximately 28,000 of those.
HPV vaccine is recommended for women age 26 or younger and men age 21 or younger. According to the CDC, it's recommended that two doses of the vaccine be given to children ages 11 or 12 within 6 to 12 months of the initial dose. Older children who get the vaccine, or those who allow more time to lapse between doses, may need an additional third dose.
Berenson and her colleagues believe this latest study is further evidence of the importance the HPV vaccine can play in individual and community health.