TORONTO -- Girls in Quebec will become the first in the country to benefit from new research that suggests the HPV vaccine is so effective that two doses -- rather than the recommended three -- may be all that's needed.
The province's health ministry has decided to forgo the third dose of HPV vaccine for girls entering Secondary 3 -- the equivalent of Grade 9 -- this fall, Karine White, a spokesperson for the ministry, confirmed in an interview. The decision was made based on a recommendation from an expert panel.
The change applies only to girls who received their first two doses of vaccine against human papillomavirus as a pre-adolescent -- age nine or 10. Girls who began the series of vaccinations after puberty will still need to get three HPV vaccine shots, said Dr. Chantal Sauvageau, who headed the committee which made the recommendation.
The province will continue to monitor emerging evidence on the efficacy of HPV vaccines, she said, and will adjust the schedule again if the need arises.
"At this time, with the scientific data available, we think two (doses) will be sufficient," said Sauvageau, who works for Quebec's National Institute for Public Health.
"But we can't predict the future. So we put mechanisms in place to closely look at what will happen in the future. And if we need another dose, we want to know it as quickly as possible."
While it is the first province to make this move, Quebec is not the first jurisdiction to decide to drop a dose of HPV vaccine from its schedule. Switzerland has moved to a two-dose regimen, with the second shot given six months after the first. That is the approach Quebec will be using.
Other provinces are watching and may follow suit, said Dr. Gina Ogilvie, medical director for clinical prevention services at the B.C. Centre for Disease Control.
"I believe actually what you're going to see with the HPV vaccine globally is increased interest in alternate dosing," Ogilvie said. "What we're increasingly recognizing is that the vaccine is so efficacious there's a good likelihood that only two doses are needed."
British Columbia has already adopted an alternate dosing schedule. The manufacturers of both available HPV vaccines -- Cervarix, made by GSK, and Gardasil, make by Merck Canada -- recommend three doses given over a six-month period.
But since 2010, B.C. has given two doses in Grade 6 and the third dose in Grade 9, piggy-backing onto other programs that take public health nurses into Grade 9 classes.
Reducing the number of doses will cut the cost of the HPV vaccine program by a third, generating significant savings for Quebec. Sauvageau's committee estimated that at current costs, Quebec will save $3 million a year by switching to a two-dose schedule.
Quebec is in a position to make the move at this point because it is one of the few provinces that starts vaccinating girls against cancer-causing HPV viruses at a young age. All provinces and territories offer the vaccine to girls for free -- and P.E.I. also makes it available to boys -- but most vaccinate girls in Grades 6 or 7 and Ontario only gives the vaccine in Grade 8.
The issue is that evidence shows pre-adolescent girls get a better immune response to the vaccine than girls or women in their teens or older. And pre-adolescent girls are less likely to have started to have sex; giving the vaccine before girls are exposed to sexually transmitted HPV viruses makes obvious sense.
Earlier this year a Canadian study published in the Journal of the American Medical Association showed that girls aged nine to 13 got as good an immune response from two doses of HPV vaccine as older teens and young women who got three doses. The governments of Quebec, Nova Scotia and B.C. funded the research.
In addition, Quebec has done its own study which confirms the results, Sauvageau said. A total of 400 girls were given two doses of HPV vaccine -- six months apart -- at nine or 10 years of age. Then, 42 months later, they were given a third dose.
Their antibody levels were higher after the third dose, but not a great deal higher than after two, Sauvageau said. "So what it was telling us was that the third dose is adding, but not a lot."
She said it may also turn out that older girls don't need three doses, but the evidence to show that hasn't been generated yet.
Moving to two doses has benefits beyond cost savings, said Ogilvie.
"I think what folks who are in the vaccine world want to do is have an effective product that does the job. And if you can give it with fewer doses, that usually would mean you have a better series completion, right? If you only need to have two doses instead of three doses it's more likely they're going to get both of those doses than three doses," she said.
"But if we have a fixed global health budget and we can reduce the vaccine costs for one vaccine program by a third -- and the program is expensive -- then that would be a prudent thing to do."
