The HPV Vaccine

Current guidance recommends the HPV vaccine for preteens as a matter of routine, and that guidance reaches into gynecology because the vaccine blocks the infections behind the cervical changes that colposcopy finds and the LEEP removes, office based procedures in Candace Cooley’s experience. The Centers for Disease Control and Prevention sets the routine age at 11 or 12, allows a start as early as 9, and recommends catch up vaccination through 26 for anyone not adequately vaccinated earlier.¹ The National Cancer Institute’s fact sheet adds that the vaccine is approved through age 45, but that routine use from 27 to 45 is not recommended, since more people in that range have already met the virus; clinicians may instead discuss it with those not vaccinated earlier.¹ In the United States the vaccine was licensed for two doses in younger recipients and three in older ones.¹ What makes the guideline unusual is its target. It is a vaccine against an infection, recommended chiefly as a defense against cancer.

A vaccine built from empty virus shells

The vaccine grew out of basic research at the National Cancer Institute. Its Center for Cancer Research recounts that by the early 1990s, once laboratory and population studies had tied particular strains of the virus to the disease, Doug Lowy and John Schiller set out to make a vaccine without using any live or killed virus, which could carry the cancer causing genes. They found that copies of one viral surface protein, L1, assemble on their own into virus like particles that are not infectious but provoke a strong antibody response.² The Food and Drug Administration approved the first vaccine in 2006 for preventing cervical cancer and genital warts in women, and in 2009 extended approval to men.² Our World in Data notes that researchers in Australia also developed an early vaccine in the 1990s, and that a 2014 version extended protection to more cancer causing types.⁹

The vaccine works the way most antiviral vaccines do. The NCI explains that it prompts the body to make antibodies that bind the virus and keep it from infecting cells, and that the particles, lacking viral DNA, cannot cause infection. It does not treat an existing infection or the disease that infection has already caused, and it does not prevent other sexually transmitted infections.¹

Figure

What the nine type vaccine covers

1. 01
   Types 6 and 11Low risk types behind 90 percent of genital warts.
2. 02
   Types 16 and 18High risk types behind about 70 percent of cervical cancers.
3. 03
   Types 31, 33, 45, 52 and 58High risk types behind another 10 to 20 percent of cervical cancers.

The vaccine now used in the United States covers nine types. Types 6 and 11 cause 90 percent of genital warts; types 16 and 18 cause about 70 percent of cervical cancers; and five more high risk types account for another 10 to 20 percent.¹ Protection is greatest when the vaccine is given before any exposure to the virus, which is why it is aimed at early adolescence, and protection against the targeted types has lasted more than a decade so far.¹

Fewer doses may be enough. The NCI’s Division of Cancer Epidemiology and Genetics reports that a randomized trial in Costa Rica found a single dose protected as well as two against infection with HPV 16, HPV 18 and the other strains most often found in cervical tumors, with effectiveness against HPV 16 or 18 of at least 97 percent in each trial group after five years.³ A single dose schedule, the researchers note, could greatly increase uptake worldwide, especially in low resource settings.³ The NCI fact sheet likewise cites evidence that one dose protects no less than two against the vaccine types.¹

On safety, the NCI states that more than two decades of monitoring have found no serious side effects, the commonest problem being brief soreness at the injection site.¹ Our World in Data describes how Japan withdrew its recommendation from 2013 to 2021 after inaccurate media reports, before large studies found no difference in side effects and the vaccine was reintroduced.⁹ Vaccination also protects people who were never vaccinated: the NCI cites falling oral HPV infection in American men as female vaccination rose, a sign of herd protection.¹ CNN, citing a study of more than 21,000 vaccinated girls and nearly 186,000 unvaccinated peers, reported no evidence that vaccination encouraged riskier behavior, a worry some parents raise.¹⁰

What population studies show

The first evidence on cancer itself came from Scotland, whose school program began in 2008. Public Health Scotland announced in 2024 that no cervical cancer had been detected in any fully vaccinated woman who received her first dose at 12 or 13.⁴ The study itself, indexed on PubMed, found no invasive cancers in women immunized at those ages whatever the number of doses, a rate of 3.2 per 100,000 in women given three doses at 14 to 22 against 8.4 in unvaccinated women, and the largest benefit in the most deprived areas.⁵

Figure

Invasive cervical cancer in Scotland by vaccination

cases in women immunized at 12 or 13, whatever the number of doses

0

incidence in women given three doses at 14 to 22

3.2 per 100,000

incidence in unvaccinated women

8.4 per 100,000

England has since reported on deaths. The Guardian described a 2026 Lancet study estimating that girls vaccinated at 12 or 13 have almost no chance of dying of cervical cancer before 30, that the relative risk of death for vaccinated women aged 30 to 34 is 63 percent lower, and that vaccination has prevented nearly 200 deaths of young women.⁶ According to EurekAlert’s account of the accompanying commentary, deaths in the vaccinated group in their early twenties fell 80 percent in 2015 to 2019, and England’s school program cut HPV infections among adolescents by 90 percent.⁷ Our World in Data reports that cervical cancer rates in the youngest vaccinated English cohort, with 89 percent coverage, ran about 87 percent below those of the oldest cohorts.⁹

The United States shows a similar pattern. CIDRAP reported that cervical cancer deaths among women under 25 fell 3.7 percent a year from the early 1990s to the mid 2010s and then 15.2 percent a year through 2021, as the first widely vaccinated generation came of age.⁸ The CCR adds that the vaccines have cut HPV infection rates in the United States by 64 percent.² The global stakes are larger still. Our World in Data cites modeling in which vaccination of 80 to 100 percent of girls and boys, with catch up for adults, could prevent nearly 50 million cervical cancers by 2100.⁹

Figure

HPV vaccination coverage in the United States

• 202178.5
• 202279.3
• 202375.9

Uptake is the weak point. CIDRAP noted coverage slipping after the pandemic, the Guardian reported English uptake down to 75 percent nationally, and CNN reported research finding that more than a third of American adults are unaware of HPV or the vaccine.⁸⁶¹⁰

The honest limit is that the vaccine is not the whole answer. It does not cover every cancer causing type, so the NCI advises vaccinated women to follow the same screening schedule as everyone else, and it cannot clear an infection already present.¹ The death data are population level, and the commentary on the English study warned that better screening and the indirect protection of unvaccinated people may have played a part, and that vaccinated women are still young; whether the protection holds into the ages when cervical cancer deaths peak is not yet known.⁷ Whether and when vaccination makes sense for a particular adult is a conversation for her and her own clinician, and for women already found to have abnormal cells the path still runs through colposcopy, as the entry on HPV and cervical cancer explains.