Human papillomavirus: 5 proven facts about the vaccine and screening

Human papillomavirus (HPV) is the most common sexually transmitted infection. In France, it causes close to 1,000 deaths from cervical cancer every year. Two tools offer protection: a vaccine offered to people aged 11 to 26, and organized screening from 25 to 65. Here are five facts established by large studies, with their figures, so you can make an informed decision.

Human papillomavirus: definition and key figures

Human papillomavirus is a family of about 200 known viruses, according to the World Health Organization. Most are harmless and cause skin warts or genital warts. About a dozen types, called “high-risk”, can transform the cells they infect. Types 16 and 18 are the most dangerous.

Transmission happens through sexual contact, including skin-to-skin contact without penetration. Condoms lower the risk without eliminating it, because the virus also lives on skin they do not cover. A large majority of sexually active people encounter HPV at least once in their lives, often in the first years of their sexual life.

Worldwide, the burden of HPV is considerable. The International Agency for Research on Cancer attributes 4.5% of all cancers to it. That represents 630,000 new cases a year (de Martel et al., 2017). The share reaches 8.6% of cancers in women and 0.8% in men. The cervix accounts for 83% of these virus-related cancers.

In France, national public health data put the number of new cases of cervical cancer at 3,159 in 2023, with about 1,000 deaths a year. Three quarters of cases occur between ages 25 and 64. Incidence has been falling since the 1990s thanks to screening.

Mechanism: how human papillomavirus causes cancer

Human papillomavirus becomes carcinogenic when it persists and hijacks the natural brakes on cell division. The process is slow. According to the World Health Organization, cervical cancer usually appears 15 to 20 years after infection in a woman with a normal immune system. This delay leaves a wide window to detect and treat lesions.

• A microscopic entry point. The virus reaches the basal cells of the epithelium through small, often invisible tears in the mucous membrane.
• Two viral proteins, E6 and E7. E6 triggers the destruction of p53, the “guardian of the genome”. E7 disables the Rb protein, which normally stops damaged cells from dividing.
• Growing genomic instability. Without these two locks, DNA copying errors pile up. The viral DNA sometimes integrates into the cell’s genome, which locks in the expression of E6 and E7.
• Graded precancerous lesions. Doctors classify them as CIN1, CIN2 and CIN3 (cervical intraepithelial neoplasia). An untreated CIN3 can progress to invasive cancer.

This mechanism explains the link with aging: genomic instability is one of the biological hallmarks of age, and the immunity that keeps the virus in check weakens over the years. An old infection that stayed silent can therefore show up late. That is why screening remains useful up to age 65.

What the science says: 5 proven facts about human papillomavirus

Five findings from national cohorts and randomized trials now shape HPV prevention. Each one rests on samples ranging from several thousand to several million people.

Fact 1: the virus is present in almost every cervical cancer

A team in Amsterdam reanalyzed an international series of 932 invasive cervical cancers, retesting the tumors first judged negative. After excluding unusable samples, HPV DNA was found in 99.7% of tumors (Walboomers et al., 1999). No other single cause of a major cancer reaches such an attributable fraction. This result underpins both vaccination and the HPV test.

Fact 2: most infections clear on their own, persistence drives the risk

In Costa Rica, 800 oncogenic HPV infections detected in 599 women were followed every six months. Two out of three (67%) had cleared after 12 months (Rodríguez et al., 2008). By contrast, when the infection persisted for at least a year, 21% of the women had a CIN2 or worse lesion within 30 months. A positive HPV test on its own is therefore not a cancer diagnosis. It simply calls for follow-up.

Fact 3: the vaccine lowers invasive cancers, especially when given early

In Sweden, 1,672,983 girls and women aged 10 to 30 were followed from 2006 to 2017 through national registries (Lei et al., 2020). After adjustment, the risk of invasive cervical cancer was 88% lower in women vaccinated against human papillomavirus before age 17. The reduction reached 53% in those vaccinated between 17 and 30.

England confirms this age effect. A national registry covers 13.7 million person-years of follow-up. Cervical cancers fell by 87% among young women offered the vaccine at 12-13 (Falcaro et al., 2021). The drop was 62% when the offer came at 14-16 and 34% at 16-18. CIN3 lesions fell by 97% in the cohort vaccinated at 12-13.

A meta-analysis covering 60 million people in 14 countries also shows a herd effect (Drolet et al., 2019). After 5 to 8 years of vaccination programs, HPV 16 and 18 infections fell by 83% in girls aged 13 to 19. Genital warts dropped by 48% in boys aged 15 to 19, even though boys were not vaccinated in most of these countries.

Fact 4: vaccine safety has been checked in hundreds of thousands of young people

A Danish and Swedish cohort followed 997,585 girls aged 10 to 17, of whom 296,826 had received 696,420 doses of the quadrivalent vaccine (Arnheim-Dahlström et al., 2013). Across 53 autoimmune, neurological or thromboembolic diseases studied, no consistent link with HPV vaccination emerged. The three initial signals showed no temporal link with the injection.

Common side effects remain local and short-lived. One trial enrolled 4,065 boys and men aged 16 to 26. Pain at the injection site affected 57% of vaccinated participants versus 51% on placebo (Giuliano et al., 2011). In the same trial, the vaccine prevented 90.4% of external genital lesions linked to the targeted types in participants who completed the full protocol.

Fact 5: the HPV test protects better than the Pap smear, even with self-sampling

Four European randomized trials compared the HPV test with conventional cytology in 176,464 women (Ronco et al., 2014). HPV testing cut the number of invasive cervical cancers by 40%. After a negative HPV test, the risk was more than three times lower than after a normal Pap smear. These data justify a 5-year interval from age 30.

Vaginal self-sampling holds up well. A meta-analysis of 56 diagnostic accuracy studies shows that PCR-based HPV tests are just as sensitive on a self-collected sample. They detect lesions as well as on a sample taken by a clinician (Arbyn et al., 2018). Mailing the kit to women’s homes multiplied participation by 2.3 among under-screened or never-screened women.

In practice: human papillomavirus vaccine and screening by age

In France, prevention relies on vaccination between 11 and 26, then on regular screening for women aged 25 to 65. The recommended vaccine is Gardasil 9, which targets nine types. According to the International Agency for Research on Cancer, these nine types account for 90% of cancers attributable to the virus worldwide.

In 2025, French health authorities extended catch-up HPV vaccination up to the 27th birthday, for women and men alike. The vaccine is reimbursed in this age group. The priority, however, remains ages 11 to 14, when two doses are enough and effectiveness is highest.

Vaccine coverage is rising but remains far from the target. At the end of 2023, Santé publique France counted 54.6% of girls and 25.9% of boys who had received at least one dose by age 15. The WHO aims for 90% of girls fully vaccinated by 15 to eliminate this cancer.

Men are affected too. In the United States, 16.3% of oropharyngeal cancers were linked to HPV in the late 1980s. That share reached 71.7% in the early 2000s (Chaturvedi et al., 2011). No organized screening exists for these throat cancers. For boys, vaccination is therefore the only lever for prevention.

To go further, our pillar page on genomic instability details how DNA damage builds up with age. How our defenses respond to viruses is explained in our article on immunity and aging. Another virus that vaccination helps prevent is covered in our feature on shingles after 50.

Advice: protecting yourself from human papillomavirus at every age

Protection against human papillomavirus combines a one-time step in adolescence with a repeated step in adulthood. The studies cited above show that each stage counts, and that neither replaces the other.

• Vaccinate early. Between 11 and 14, two doses are enough and the effect on cancer is strongest. In France, the school campaign for 12- to 13-year-olds makes this possible without a doctor’s appointment.
• Catch up until 26. An unvaccinated young adult can still receive three doses of HPV vaccine, reimbursed, even after becoming sexually active.
• Respond to screening invitations. In France, women aged 25 to 65 receive a letter from the national health insurance. The sample can be taken by a doctor, a midwife or a laboratory.
• Ask for self-sampling if something holds you back. For women who avoid the gynecological exam, this home test offers the same reliability with a PCR technique.
• Keep up screening after vaccination. The vaccine does not cover every high-risk type, and many adult women were vaccinated late or not at all.
• Quit smoking. Smoking is a recognized cofactor in the persistence of the virus and the progression of cervical lesions.

After 65, stopping screening is something to discuss with your doctor based on your test history. A woman who has never been screened, or poorly followed up, benefits from an HPV test, even late. To receive our monthly study summaries on prevention, subscribe to our health newsletter, or reread our 8 preventive health habits.

Frequently asked questions about human papillomavirus

How is human papillomavirus transmitted?

Human papillomavirus is mainly transmitted through sexual contact, with or without penetration, by simple contact between skin or mucous membranes. Condoms reduce the risk but do not eliminate it, because the virus can be found on areas they do not cover. Infection is very common in the first years of sexual life, and it usually goes unnoticed, with no symptoms at all.

Why vaccinate boys against HPV?

Boys transmit the virus and can develop cancers of the anus, penis and throat. In the United States, the share of oropharyngeal cancers linked to the virus rose from 16% to 72% in twenty years. No screening exists for these cancers in men. In France, vaccinating boys aged 11 to 14 has been recommended since 2021.

Is the HPV vaccine useful after age 20?

Yes, up to the 27th birthday, but its benefit declines with age. In Sweden, the risk of cervical cancer fell by 88% in women vaccinated before 17 and by 53% in those vaccinated between 17 and 30. The vaccine protects against the types a person has not yet encountered. It does not cure an infection that is already established.

What is the difference between a Pap smear and an HPV test?

The Pap smear, or cytology test, looks for abnormal cervical cells under a microscope. The HPV test detects the DNA of high-risk human papillomavirus types, which means the cause of the lesions. In four European trials, the HPV test cut invasive cancers by 40% compared with the Pap smear. It is recommended every 5 years between 30 and 65.

Do I still need screening if I have been vaccinated?

Yes. The Gardasil 9 vaccine targets nine HPV types, responsible for about 90% of virus-related cancers, but not all of them. Many women were also vaccinated after a first exposure. Screening therefore remains recommended from 25 to 65, on the same schedule as for an unvaccinated woman.