New research suggests one dose of an HPV vaccine may be enough to protect teenage girls against cervical cancer.
Officials say the current recommendations call for three doses but only a small percentage of girls actually complete the treatment.
The study out of Costa Rica found those who got just a single dose of the vaccine had stable antibodies against the virus for four years.
Researchers say it is too soon to change policy guidelines.
They say they also still need to study the effects of the Gardasil vaccine, which is the vaccine used most often in the United States.