Dalhousie University and the P.E.I. Department of Health are working together on a new study of the effectiveness of the human papillomavirus vaccine.

The HPV is a sexually transmitted virus linked to the development of cervical cancer, and the vaccine is currently being offered free to young girls in all provinces and territories. In some provinces the vaccine is being offered in two doses, while others provide three doses.

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It is still not known how long the protection of the HPV vaccine lasts, says Dr. Heather Morrison. (CBC)

"What we want to determine is how the two-dose schedule given in some provinces compares to the three-dose schedule given here in Prince Edward Island," said Dr. Shelly McNeil, a lead researcher on the study, and an infectious disease specialist at Dalhousie University.

"We want to follow girls over the long term to see how effective the vaccine has been over time."

The study, known as QUEST, will follow more than 8,500 teenage girls recruited from British Columbia, Alberta, Quebec and the Maritimes for up to 10 years. It will assess risk factors, frequency of infection with HPV, and the level of protection provided by two doses of vaccine compared to three.

"It is not known how long this protection lasts, or whether there is any difference in effectiveness between two doses or three doses of HPV vaccine," noted P.E.I. chief public health officer Dr. Heather Morrison.

A study completed earlier this year of 520 girls by a University of British Columbia researcher found that two doses may be as effective as three, but that more study is needed.