One-dose HPV vaccine program becomes more efficient in Canada

In Canada, switching to a gender-neutral one-dose vaccination program for human papillomavirus (HPV) will result in more efficient use of vaccine doses compared to a two-dose program, new modeling shows. It may be possible to prevent similar cases of cervical cancer. analysis.

Even in the most pessimistic scenario, all one-dose vaccination options would be “significantly more efficient” than two-dose programs if vaccine protection remains high during peak sexual activity. So, the study authors wrote.

Furthermore, this scenario predicted that cervical cancer would be eliminated in Canada between 2032 and 2040. HPV can also cause oral, throat, and penile cancer, most of which are preventable through vaccination.

“The COVID-19 pandemic is having an impact on HPV vaccination in Canada, especially among vulnerable populations,” says study author, infectious disease consultant and associate professor of social and preventive medicine at the Quebec National Institute of Public Health. said Chantal Saubergaard, MD, PhD. at Laval University in Quebec City, Quebec, Canada.

Switching to one-dose vaccinations would offer potential economic savings and program flexibility, he added. This change could also enable investments aimed at increasing vaccination coverage in areas with suboptimal coverage and subgroups with high HPV burden. Such efforts could help cushion the pandemic's impact on health programs and reduce inequalities, Saubergaard said.

the study published Online on October 7th CMJ.

Changes in vaccination program

Since the World Health Organization's Expert Strategic Advisory Group on Immunization issued its recommendation for a single dose in 2022, countries around the world have been considering whether to shift their HPV vaccine strategies from two to one doses.

In July, Canada's National Advisory Committee on Immunization (NACI) Updated guidelines A single-dose approach is recommended for ages 9 to 20 years. The changes will bring Canada into line with 35 other countries, including Australia and the United Kingdom. Canada's Vaccine Advisory Group still recommends two doses for people aged 21 to 26 and three doses for people who are immunocompromised or infected with HIV.

To help inform new NACI policy, Sauvageau et al. used HPV-ADVISE, an individual-based transmission dynamics model of HPV infection and disease, to explore several single-dose and two-dose strategies. I modeled it. They looked at vaccination programs in Quebec, which has a high HPV vaccination rate of about 85%, and Ontario, which has a low vaccination rate of about 65%.

The researchers tested noninferiority (98% efficacy) and pessimistic (90% efficacy) scenarios for the one-dose program, as well as various average vaccine durations, including lifetime, 30-year, and 25-year coverage. was analyzed. They compared the scenario with a two-dose program with 98% efficacy and lifetime duration, and found a relative reduction in the incidence of HPV-16 infection and cervical cancer, and one case of cervical cancer. The number of doses required to prevent the disease was estimated.

Overall, this model suggests that a two-dose or non-inferior, one-dose, gender-neutral HPV vaccine program would nearly eliminate HPV-16 infections in Quebec by 2040-2045 and reduce infections by 90% in Ontario. predicted to decrease by more than %. Under a one-dose strategy with vaccine efficacy of 90%, a rebound in HPV-16 infections begins 25 to 30 years or more after switching to a lower-dose strategy, allowing authorities to detect signs of declining efficacy. This will give them time to make changes. Policies can also be created as needed, the authors write.

Additionally, the model predicted that a non-inferior, one-dose, gender-neutral HPV vaccination program would avert a similar number of cervical cancer cases compared to a two-dose program. Compared to those who had not been vaccinated, the reduction would be about 60% in Quebec and 55% in Ontario. In the most pessimistic scenario with a 25-year vaccination period, a one-dose program would be slightly less effective in preventing cancer, about 3% less effective than a two-dose program over 100 years.

All single-dose scenarios are projected to lead to cervical cancer elimination in 8 to 16 years, resulting in fewer than 4 cases of cervical cancer per 100,000 women.

Single-dose programs also lead to more efficient use of vaccine doses, with approximately 800 to 1000 doses required to prevent one case of cervical cancer in a single-dose program; More than 10,000 additional doses would be required to prevent one additional case of cervical cancer. Two-dose program.

What's next?

In Canada, the HPV vaccine is authorized for patients aged 9 to 45 years. Current youth and young adult immunization rates vary by state and are below the national goal of 90%. in July 2024 UpdateNACI estimated that 76% of 14-year-olds, both male and female, will have received at least one vaccination, and 67% will have received two vaccinations by 2023. Vaccine uptake was slightly higher in girls than in boys.

Moving to a one-dose schedule to increase vaccination rates could not only maintain the vaccine's effectiveness but also appeal to younger people.

“If you look at the studies published around the world, the efficacy of a single dose of HPV vaccine is actually very high,” said Caroline Quack Tan, professor of microbiology, infectious diseases, immunology and pediatrics at the university. said the M.D. Ph.D. Originally from Montreal, Quebec, Canada.

Kwaktan, who was not involved in the study, previously served as NACI chair and currently chairs Quebec's immunization committee.

“When it comes to preventing HPV infections that can lead to cancer, one dose or two doses provide essentially the same amount of protection,” she says.

But not all doctors agree on switching vaccination approaches. In early October, the Canadian Federation of Women Physicians A report has been published It includes 12 recommendations to increase HPV vaccination rates, including a call for health care providers to continue with multiple vaccination schedules at this time.

“Vaccination is the most powerful action we can take to prevent HPV-related cancers. Canada is falling behind, but if we act quickly we can get back on track.” '' said Dr. Vivian Brown, chair of the group's HPV immunization task force. He is the chair and co-founder of Canadian HPV Prevention Week and a past president of the federation.

After the July NACI update, a task force evaluated the risks and benefits of single-dose vaccine regimens, he said. They concluded that the multiple-dose schedule should be continued at this time because of its proven efficacy.

“Until further research into the effectiveness of single-dose schedules is available, healthcare providers and public health organizations should continue to offer multiple-dose schedules to patients,” Professor Brown said. “This is the only way to ensure that individuals are protected against HPV infection and cancer over the long term.”

This research was supported by the Public Health Agency of Canada, the Canadian Institutes of Health Research, the Bill & Melinda Gates Foundation, and the Canadian Immunization Research Network. Saubergaard, Kuatan and Brown declared that they had no relevant financial disclosures.

Carolyn Crist is a health and medical journalist reporting on the latest research for Medscape Medical News, MDedge, and WebMD.