Quebec has achieved herd immunity to HPV: study

The human papillomavirus (HPV) vaccination program has reportedly achieved a degree of herd immunity less than twenty years after its implementation in Quebec, according to research conducted at Université Laval.

The program is so effective that even unvaccinated young people benefit from a form of immunity, Dr. Chantal Sauvageau’s team found.

“We have shown a reduction in the types of HPV most likely to lead to cancer, including in people who have not been vaccinated,” summarized the professor at Université Laval’s Faculty of Medicine. “This is what we call herd immunity.”

The human papillomavirus family includes more than 100 types of viruses. There are HPVs with a low risk of cancer and a dozen HPVs with a high risk of causing cancer. HPVs are primarily transmitted sexually.

HPV is present in virtually all cases of cervical cancer. It also causes genital or anal warts, as well as lesions that can lead to cancers of the throat, vagina, vulva, anus, and penis.

The team led by Professor Sauvageau measured the prevalence of HPV in 369 sexually active, unvaccinated young men aged 16 to 20, recruited between September 2020 and August 2022.

They found that the prevalence of the four HPV types covered by the first vaccines used in Quebec was 0.5 per cent.

In contrast, a Quebec study conducted on people aged 18 to 24 before the vaccination program was implemented revealed that HPV type 16 was the most prevalent in this group and was detected in 16 per cent of men.

This means, Dr. Sauvageau clarified, that HPV circulation has become so low that even unvaccinated people “benefit from a form of protection attributable to herd immunity.”

“These are vaccines that work at over 95 per cent,” the researcher said. “When we can vaccinate before the onset of sexual activity, it produces the results we see here when we have good vaccination coverage.”

In the United States, where vaccination coverage is less widespread, we are also seeing a form of herd immunity, but on a lesser scale, Dr. Sauvageau added.

The recent, highly publicized upsurge in measles cases clearly demonstrates what can happen when vaccination coverage declines, she said.

The HPV vaccination program was rolled out in Quebec in 2008. Initially offered to girls aged 9 to 17, it was expanded to boys in 2016. Today, the vaccine protects against nine types of the virus and is offered to young people aged 9 to 20.

The findings of this study were published in The Journal of Infectious Diseases.

–This report by La Presse Canadienne was translated by CityNews