Study: For HPV, two shots may be enough
A new study conducted by the National Cancer Institute has found that two doses of the HPV vaccine may be just as effective as the recommended three-dose schedule. The findings are important because vaccine costs and scheduling problems often prevent women from receiving all three recommended shots.
The study followed 7,466 women in Costa Rica who received either Cervarix or the hepatitis A vaccine. About 20% of the Cervarix group didn't get all three doses of the vaccine. Four years later, the women who'd received only two doses had protection rates comparable to those who finished the full treatment regimen. Additionally, even women who'd only gotten one shot experienced increased protection from the virus.
"Our study provides evidence that an HPV vaccine program using two doses will work. It may be that vaccinating more women, with fewer doses for each, will reduce cervical cancer incidence more than a standard three-dose program that vaccinates fewer women," NCI investigator Aimee Kreimer tells the Seattle Times.
Researchers note further study is needed to see if long-term protection rates are similar to those found in the study. And the Costa Rica trial primarily tracked women between the ages of 18 and 25. In the U.S., it's recommended that girls ages 11 and 12 receive the shot, so more data is necessary to see if protection with fewer doses applies this age cohort. The findings appear in the Journal of the National Cancer Institute.