Written by Faculty of Medicine
University of British Columbia researchers have provided the most conclusive evidence that two doses of the human papillomavirus (HPV) vaccine provides just as much protection – for as long as five years – as the previous standard regimen of three doses.
Professor Gina Ogilvie
The longest examination so far of the most widely-used version of the HPV vaccine shows there is no need for young people under the age of 15 who received 2 doses to get a booster shot within the first five years of receiving the second dose.
Published in the Journal of the American Medical Association, the study provides the most definitive confirmation yet that recent moves to a two-dose regimen by most countries is sound, thus lowering financial and logistical barriers to implementing the most effective tool for preventing cervical cancer.
“A decade after introducing the HPV vaccine in British Columbia, about a third of the province’s eligible population still isn’t getting it, and the rates are far lower in the developing world,” said School of Population and Public Health Professor Gina Ogilvie. “Two doses are less expensive, and involve less effort by patients and health care providers.
“By reassuring governments and health organizations that two doses are just as protective as three, we can move closer to the goal of near-universal HPV vaccination, and speed the day when cervical cancer is eradicated.”
Professor Gina Ogilvie
HPV, which is commonly transmitted through sexual activity, is estimated to infect more than 70 per cent of sexually-active Canadians. The body’s natural defenses usually clear away the infection without a person noticing any symptoms. In some cases, however, the infection persists, leading to cervical, vaginal and vulvar cancer in women, penile cancer in men, and genital warts in women and men. HPV is the leading cause of cervical cancer.
Until a few years ago, girls received a first dose between ages 9 and 13, followed by a second one two months later, and a third one six months after the first. But global and national health agencies began cutting back to two doses based on several studies, including a one by UBC published four years ago that reported on antibody levels three years after the second dose.
The latest study examined the level of HPV antibodies in a smaller subset of the girls in the 2013 study, checking in on them five years after their second dose of the vaccine. Although antibodies circulating in the blood decreased from year 3 to year 5, they fell by the same amount for girls who received two doses as for girls who received three.
In September, British Columbia will begin giving the vaccine to boys, as well as girls, starting in Grade 6. Six other Canadian provinces are already providing the vaccine to boys and girls.
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