More countries are dropping the number of doses needed for HPV vaccines. Should Canada?
As of this fall, teenagers in England will receive just one shot of HPV – making it the latest country to drop the number of doses required for the highly effective vaccines known for protecting against a range of cancers.
The World Health Organization (WHO) announced more than a year ago that a single dose provides “solid protection” against human papillomavirus (HPV) comparable to two or three injections, based on a growing body of global evidence. Ireland, Scotland, Wales and Australia have already made the switch. And many researchers say providing fewer doses could free up much-needed resources for other public health efforts.
So should Canada follow the lead of other countries in adopting a single-dose approach? There’s no decision here yet.
The country’s top vaccine advisors are reviewing “all available evidence” as they conduct their own analysis based on Canadian disease rates and model projections, a spokesperson for the Public Health Agency of Canada told CBC News. That work is “expected to be completed next year”.
Currently, Canadian guidelines suggest that healthy children ages nine to 15 should receive one of the available HPV vaccines on a two- or three-dose schedule.
Current Chair of Quebec’s Immunization Commission, Dr. Caroline Quach — who chaired NACI during much of the COVID-19 pandemic — is among Canadian medical experts who say Canada should consider following the example of England and other countries to follow.
Effectiveness of one dose ‘quite high’
“If you look at the studies that have been published around the world … the effectiveness of one dose of the HPV vaccine is actually quite high,” Quach said.
“In terms of preventing HPV infections that can lead to cancer, you’re basically giving the same amount of protection whether you give one dose or two doses.”
Research from India and Costa Rica has shown that one dose of certain types of HPV vaccines has a ten-year shelf life, noted the UK’s Vaccination Advisory Board.
The UK also looked at a more recent trial in Kenya, which also aimed to study the effectiveness of a single dose. That study found that young girls and women were effectively protected against HPV infection for 18 months after vaccination — with vaccine efficacy greater than 97 percent, keeping the results consistent with three-dose studies.
“Each country and advisory committee needs to look at the data and look at the modeling, their own country’s epidemiology,” Quach noted. “But it’s definitely something we need to look at.”
LOOK | Concerns over lagging childhood HPV vaccination rates:
Medical experts are concerned about the impact of missed HPV vaccinations on children due to pandemic school closures. They want schools and pharmacies to do their best and make sure children get their HPV vaccinations to protect them from cancer later in life.
Dawn Bowdish, an immunologist at McMaster University in Hamilton, Ont., said a cautious approach is wiser in gauging whether a reduced number of doses required maintains decades of protection.
Most childhood vaccines require multiple doses to train the immune system enough to recognize a long-term threat, she added. And even with less HPV circulating in Canada thanks to years of HPV vaccination efforts, she said the country is still in a “delicate place.”
“The tide could turn very quickly if we lose the benefit of vaccination,” Bowdish warned. “We haven’t eliminated this virus — it’s ready to come back and find vulnerable people again.”
However, Quach stressed that if Canada takes the single-dose route, robust surveillance programs would picking up early warning signs if the approach falls short, it suggests that the country should change course and offer overtaking shots.
And both agree that there is a key element to the whole debate about the ideal number of doses: money.
“The UK’s gamble is that one dose will be enough…but they felt the cost benefit was worth it,” Bowdish said. “It would be cheaper to administer one dose, and easier than having someone come back three times.”
The resources freed up by the upcoming single-dose move could be redirected, “improving our already high vaccination coverage and ensuring that anyone who misses their dose still has other opportunities to receive it,” said Mark Jit, an epidemiologist at the London School of Hygiene & Tropical Medicine and a member of the Single Dose HPV Vaccine Consortium, in a statement.
On a global level, advocates say reducing the number of doses needed could be a huge cost-cutting measure for vaccinating populations in low- and middle-income countries.
LOOK | Kids lagging behind after pandemic school closures:
School-age children in Ontario are far behind on routine vaccinations, in part due to pandemic school closures, according to new research from the University of Toronto.
High cost for adults who want the injections
But what the shift should not solution here in Canada is the skyrocketing costs adults face as they age without government vaccination programs.
For example, in Ontario, students in 7th grade can get the HPV vaccine for free. Public health clinics also usually offer the injections free of charge for students through grade 12, and for gay, bisexual, and trans men up to age 26.
Other young adults who want the injections but don’t qualify for free programs can spend about $600 on three required doses, said Gillian Cameron, a resident of London, Ont., an advocate for wider access to HPV vaccines. (The vaccines can be purchased privately with a prescription and may be covered by some insurance companies.)
Cameron is now calling on the Ontario government to provide free HPV shots to anyone under the age of 26 — and so far more than 30,000 people have signed her online petition.
“It was sort of a question like, are you going to pay your phone bill this month? Are you going to pay for the groceries? Or are you going to get this vaccine?” she said.
That’s a choice no Canadian should make, Cameron added, given the overwhelming evidence that these injections save lives by preventing infections that can lead to potentially deadly cancers of the cervix, anus and head and neck.
An HPV vaccine was first recommended in the US in 2006, and over the next 10 years, quadrivalent-type HPV infections fell by 86 percent in female teens ages 14 to 19 and by more than 71 percent in women from early 20s. says the US CDC.
And on the cancer front, a UK study published in The Lancet in 2021 cervical cancer rates found were 87 percent lower in young women who were eligible for HPV vaccination when they were 12 to 13 years old, compared to young women who had not received a vaccination.
As NACI continues to assess the ideal number of doses, there is international consensus on the astonishing overall success of these vaccines.
“The fact that we have a vaccine that can prevent cancer… how amazing is that?” said Bowdish.
