HPV, or human papillomavirus, is the most common sexually transmitted infection in the United States, and about 80% of women will get at least one type during their lifetime. Most of those infections cause no symptoms and disappear on their own, but certain strains can lead to cervical cancer and other serious health problems. Roughly 79 million Americans are currently infected.
How HPV Spreads
HPV spreads most commonly during vaginal or anal sex, but it can also pass through close skin-to-skin touching during sexual contact. Condoms reduce the risk but don’t eliminate it entirely, since the virus can live on skin that a condom doesn’t cover. Many people carry HPV without knowing it, which is why it circulates so widely.
High-Risk vs. Low-Risk Strains
There are over 100 types of HPV, but they fall into two broad categories that matter for your health: low-risk types and high-risk types.
Low-risk strains, especially types 6 and 11, cause genital warts. These appear as small, flesh-colored bumps that can be flat or raised, sometimes clustered in a cauliflower-like shape. Over 90% of genital wart cases trace back to these two strains. Warts are treatable and not cancerous, though they can recur.
High-risk strains are the ones linked to cancer. Types 16 and 18 together cause about two-thirds of all cervical cancers worldwide, with type 16 alone responsible for roughly half. Five additional high-risk types (31, 33, 45, 52, and 58) account for another 15% of cervical cancers. Beyond the cervix, high-risk HPV can also cause cancers of the vagina and vulva. High-risk strains are detected in 99% of cervical precancers. FDA-approved tests screen for up to 14 high-risk types.
Why Most Infections Never Become Cancer
About 90% of women clear HPV infections on their own within 6 to 18 months. Your immune system recognizes the virus and eliminates it without any treatment. During that window, you likely won’t know you have it, since high-risk HPV almost never causes symptoms on its own.
The danger comes from the infections that don’t clear. When a high-risk strain persists for years, it can gradually change cervical cells from normal to mildly abnormal, then moderately abnormal, and eventually severely abnormal. That progression from infection to precancer to cancer typically takes a decade or more, which is exactly why routine screening is so effective at catching problems early.
Cervical Cancer Screening Guidelines
Screening recommendations from the U.S. Preventive Services Task Force are based on your age:
- Under 21: No screening recommended, regardless of sexual activity.
- Ages 21 to 29: A Pap test every 3 years. HPV testing alone is not recommended in this age group because HPV infections are so common in younger women and almost always resolve.
- Ages 30 to 65: Three options. A Pap test every 3 years, a high-risk HPV test every 5 years, or both tests together (called cotesting) every 5 years.
- Over 65: No further screening if you’ve had adequate prior screening and are not at high risk.
- After hysterectomy: No screening needed if the cervix was removed and you have no history of high-grade precancerous changes or cervical cancer.
What Happens After an Abnormal Result
An abnormal Pap or positive HPV test does not mean you have cancer. It means your cells need a closer look. Your provider will weigh several factors: your current result, any previous screening results, past treatments for cervical cell changes, and your age. Based on that overall risk picture, the recommendation typically falls into one of three paths: repeat testing in 1 or 3 years, a colposcopy, or (rarely at this stage) treatment.
A colposcopy is a short office procedure. A speculum is placed to view the cervix, a mild vinegar solution is applied to highlight abnormal areas, and a magnifying instrument lets the provider examine the tissue up close. In most cases, a small biopsy is taken at the same time so the cells can be examined under a microscope.
Biopsy results are graded on a scale of 1 to 3, describing how abnormal the cells are. Grade 1 changes are mild and usually resolve without treatment. Grade 2 changes are moderate and typically treated by removing the abnormal tissue, though in some cases a provider may recommend monitoring with repeat biopsies every 6 months. If grade 2 changes persist for 1 to 2 years or progress, treatment becomes necessary. Grade 3 changes are severe. They are not cancer, but they can become cancer if left untreated, so they are treated right away.
HPV Vaccination
The HPV vaccine prevents new infections from the strains most likely to cause cancer and genital warts. It works best when given before any exposure to the virus, which is why routine vaccination starts at age 11 or 12. But the vaccine is approved and recommended through age 26 for anyone not already fully vaccinated.
For adults ages 27 through 45, vaccination is available through shared decision-making with a provider. In clinical trials of women ages 24 to 45 who had never been exposed to the vaccine-targeted strains, the vaccine was about 89% effective at preventing persistent infections and precancerous changes. That number dropped to about 47% when the analysis included women who already had prior exposure to those strains, since the vaccine prevents new infections but does not treat existing ones or speed up clearance of a current infection.
More than 90% of HPV-caused cancers are preventable with vaccination. Even if you’ve already had one type of HPV, the vaccine can still protect you against other strains you haven’t encountered. If you’re under 26 and haven’t been vaccinated, there’s a clear benefit. If you’re older, the potential benefit depends largely on your likelihood of encountering new HPV types in the future.