New research shows a decline in the number of females receiving all three doses of the human papillomavirus vaccine between 2006, when it was approved, and 2009.

Abbey Berenson and Jacqueline Hirth of the University of Texas Medical Branch and co-investigators studied data for nearly 272,000 privately insured females who started the vaccine series. While the overall number of girls who received the first shot in the series rose during the study period, the percentages of those who got all three dropped from roughly 50 percent in 2006 to just over 20 percent in 2009.

Females age 13 and older were less likely than those ages nine to 12 to receive all three shots. Females who completed the series were more likely to have been vaccinated by their OB/GYN than by their pediatrician.

The second dose of HPV vaccine should be given one to two months after the first, with the third and final shot administered within six months of initiation. Yet just over 38 percent who got the first shot completed the series within one year. The study did investigate the reasons for non- completion.

Berenson said a goal of the study was to alert parents to the importance of getting all three shots. According to the researchers, physicians may not be doing enough to ensure that the series is completed. And the marketing campaign that began in 2006 "never addressed the three shots," said Berenson. The website for Gardasil, one of two approved HPV vaccines, does note that the immunization is given in three shots.

[PNU editor's note: The study, "Completion of the Human Papillomavirus Vaccine Series Among Insured Females Between 2006 and 2009," was published in the journal Cancer (2012;doi:10.1002/cncr.27598).]

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