Two doses of HPV vaccine gave girls aged 9 to 14 years as much protection as three doses against genital warts, and both regimens provided significantly more protection than one dose or no doses at all, according to research recently published in Sexually Transmitted Diseases.
Researchers suggest that their findings are another piece of the growing body of evidence to support administering HPV vaccinations at a young age.
Rebecca B. Perkins
The study is the first clinical evidence published that supports the CDC’s two-dose recommendation schedule, according to a press release.
“The majority of data supporting the two-dose schedule was based on antibody responses,” Rebecca B. Perkins, MD, MSc, department of obstetrics and gynecology, Boston Medical Center, told Healio Family Medicine. “I wanted to demonstrate that this regimen would be effective at preventing HPV disease.”
Researchers used the Truven Health Analytics Marketscan administrative database to compare rates of genital warts among 387,9036 females aged 9 to 18 years receiving zero, one, two or three doses of HPV vaccine. The exposure period began on Jan. 1, 2007, or the date of the final HPV dose, and lasted until the first diagnosis of genital warts or Dec. 31, 2013. Researchers then performed multivariable Poisson regression to determine the risk for genital warts associated with vaccine doses.
Perkins and colleagues found that the mean age was 14.73 years and the mean exposure period was 5.64 years. In addition, the proportion who received zero doses was 52.1%, one dose was 7.8%, two doses was 9.4%, and three doses was 30.7%. The rate of genital warts was 1.97 per 1,000 person-years, and those who received zero or one dose experienced more genital warts than those who received three doses. The effectiveness of two doses following current CDC guidelines was similar to three doses, and the risk for genital warts increased with age.
“At this point we have overwhelming evidence that HPV vaccination prevents genital warts and pre-cancers of the cervix. We also know that it works better when given at younger ages. So, all primary care doctors should make every effort to protect their patients by ensuring that they start the vaccine series at age 11,” Perkins told Healio Family Medicine. “Specifically, from this study, primary care physicians should feel confident that recommending two doses of HPV vaccination to all of their patients ages 14 and younger is as effective as three doses at preventing genital warts.” – by Janel Miller
The researchers report no relevant financial disclosure.