Yes, HPV (human papillomavirus) is a sexually transmitted infection. It is, in fact, the most common one in the United States. About 85% of people will get an HPV infection during their lifetime, and roughly 13 million Americans become newly infected each year. The reason you might see it called an “STI” rather than an “STD” comes down to an important distinction: most HPV infections never cause symptoms or disease, so health authorities like the CDC increasingly prefer the term “infection” over “disease.”
STI vs. STD: Why the Terms Matter for HPV
A sexually transmitted infection is any virus, bacterium, fungus, or parasite passed through sexual contact. A sexually transmitted disease is what develops when that infection actually produces symptoms. Since the vast majority of HPV infections clear on their own without ever causing warts, cancer, or any noticeable problem, calling HPV an “STD” can be misleading. You can carry the virus, pass it to a partner, and never know you had it.
The CDC now uses “STI” as its default term, reserving “STD” mainly when referencing older data sets that used that label. In practical terms, HPV fits both categories. It is always an STI, and it becomes an STD only when it causes visible disease like genital warts or leads to cell changes that progress toward cancer.
How HPV Spreads
HPV spreads most commonly during vaginal or anal sex, but it does not require fluid exchange the way some other infections do. Close skin-to-skin contact during sex is enough. This means condoms reduce the risk but don’t eliminate it entirely, because the virus can live on skin that a condom doesn’t cover. Nearly everyone who is sexually active and unvaccinated will encounter HPV at some point.
Most Infections Clear on Their Own
Your immune system handles HPV effectively in most cases. About 70% of infections resolve within one year, and around 90% clear within two years. During that window, you can still transmit the virus to partners even if you have no symptoms. The infections that don’t clear are the ones that raise health concerns, particularly when they involve high-risk strains.
Low-Risk vs. High-Risk Strains
There are dozens of HPV types, and they fall into two broad categories. Low-risk strains rarely cause serious problems. Their main consequence is genital warts, which are small bumps that can appear on or around the genitals, anus, mouth, or throat. In rare cases, low-risk HPV causes warts in the respiratory tract that can interfere with breathing.
High-risk strains are a different concern. There are 12 of them, and two, HPV 16 and HPV 18, are responsible for most HPV-related cancers. These strains don’t cause warts. Instead, they can trigger slow cell changes over years or decades that eventually become cancerous. An estimated 39,300 cancers per year in the U.S. are attributable to HPV, including roughly 8,100 cervical cancers, 4,600 anal cancers, and 1,900 throat cancers. More than 42 million Americans currently carry HPV types known to cause disease.
Testing Differences for Men and Women
Cervical screening (Pap tests and HPV tests) can detect high-risk HPV in women before it causes cancer, which is why routine screening starting at age 25 is so effective at catching problems early. For men, there is no approved routine HPV test. Most men who carry HPV never develop symptoms, and those who do typically notice genital warts. Cancers caused by HPV in men, particularly throat and anal cancers, are usually diagnosed only after symptoms appear.
How the Vaccine Works
The current HPV vaccine protects against nine strains: the seven types responsible for most HPV-related cancers (types 16, 18, 31, 33, 45, 52, and 58) and the two low-risk types that cause most genital warts (types 6 and 11). In clinical trials, the vaccine showed roughly 88% efficacy against persistent infection and related cell changes in women aged 24 through 45.
The recommended schedule depends on age. Children and teens who start between ages 9 and 14 need only two doses, spaced 6 to 12 months apart. Anyone who starts at age 15 or older needs three doses over about six months. Routine vaccination is recommended at age 11 or 12, with catch-up vaccination available through age 26. Adults 27 through 45 who haven’t been vaccinated can still get the vaccine after discussing it with a healthcare provider, though the benefit is smaller since most people in that age range have already been exposed to at least some HPV types.
The vaccine works best before any exposure to HPV, which is why it’s recommended well before most people become sexually active. It does not treat existing infections or clear strains you’ve already contracted, but it still protects against the other targeted strains you haven’t encountered yet.
Why HPV Is So Common
Three factors make HPV unusually widespread. First, it spreads through skin contact rather than requiring bodily fluids, so barrier methods only partially prevent transmission. Second, most carriers have no idea they’re infected because the virus produces no symptoms in the majority of cases. Third, there’s no routine screening for men, which means half the population has no practical way to check their status. The combination means HPV circulates freely through sexually active populations, making vaccination the most reliable form of prevention.