Girls who are vaccinated against HPV are not only well protected against cervical cancer; they are also less likely to develop severe precancerous lesions of the vulva and vagina, particularly if they were vaccinated before the age of 17. This is shown in a new study from Karolinska Institutet published in JAMA Oncology.
In Sweden, all children in middle school are offered vaccination against human papillomavirus (HPV), which protects against cervical cancer, among other things. HPV can cause high-grade, precancerous lesions and cancer in different parts of the genital area. Researchers at Karolinska Institutet have now shown that the quadrivalent HPV vaccine, which protects against HPV types 6, 11, 16 and 18, can be linked to a reduced risk of high-grade lesions of the vulva and vagina.
Early vaccination is crucial
The study is based on data from more than 770,000 women born between 1985 and 1998 and living in Sweden between 2006 and 2022. The researchers used Swedish health registries to follow the participants over time. They compared the incidence of high-grade lesions of the vulva and vagina in women who had received at least one dose of the HPV vaccine and women who had not been vaccinated.
After adjusting for factors such as age, education, income and maternal medical histories, the results showed that the risk of these severe lesions was 37 percent lower in vaccinated women than in unvaccinated women. The protection was strongest in women who were vaccinated before the age of 17, who had a 55 percent lower risk compared to unvaccinated women.
"Our study is the largest of its kind to investigate the link between HPV vaccination and serious diseases of the vulva and vagina," says the study's first author, Yunyang Deng , postdoctoral researcher at the Department of Medical Epidemiology and Biostatistics , Karolinska Institutet. "The results highlight the importance of offering the HPV vaccine to girls at an early stage in life, before they become sexually active."
Study other forms of cancer
The researchers now plan to investigate how effective different types of HPV vaccines are and how long the protection lasts.
"We also want to study the vaccines' effect on other HPV-related cancers, including in men." says Jiayao Lei , assistant professor at the Department of Medical Epidemiology and Biostatistics and the Center for Cervical Cancer Elimination at the Department of Clinical Science, Intervention and Technology , Karolinska Institutet, who led the study.
The research was conducted in collaboration with the Public Health Agency of Sweden and Karolinska University Hospital. It was funded by the Swedish Research Council, the Swedish Cancer Society, Forte, Karolinska Institutet's strategic research area in epidemiology and biostatistics, and the EU's Horizon 2020 programme. The researchers report no conflicts of interest.
Publication
"Quadrivalent human papillomavirus vaccine and high-grade vulvovaginal lesions" , Yunyang Deng, Shiqiang Wu, Lina Schollin Ask, Tiia Lepp, Mark Clements, Hanna Milerad, Christina Carlander, Jiayao Lei, JAMA Oncology, online 18 December 2025, doi: 10.1001/jamaoncol.2025.5511.
Facts about HPV vaccines
There are many types of human papillomavirus (HPV), but it is HPV types 16 and 18 that cause most cases of cervical cancer. In particular, HPV 16 contributes substantially to anal cancer and throat cancer, as well as cancer of the vulva, vagina and penis. Several HPV vaccines with varying degrees of protection have been approved in Sweden and internationally. They all protect against HPV 16 and 18.
Source: Public Health Agency of Sweden and Jiayao Lei.
