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HPV Notes

2026 Apr 06

What am I infected with?

I'm infected with HPV, or human papillomavirus (Wikipedia). It's quite common.1 There are over 200 strains — about 50 of the strains are sexually transmitted, and the rest just live on your skin. Most HPV infections have no symptoms and clear on their own (90% of women clear it within 2 years), but some strains cause genital warts and some can lead to cancer.

(In fact, all warts are caused by some strain of HPV.2 Supposedly the strains that cause cancer are distinct from the ones that cause warts.3)

The strains of HPV that people pay the most attention to are:

There are ~16 strains that are linked to causing cervical cancer.4

When I first tested positive for HPV in 2021, Kaiser told me that I had one of the strains in the "second tier" of risk for cervical cancer (i.e., not HPV-16 or 18). The exact language from my test results:

Specimen is POSITIVE for any one or combination of HPV DNA type 31, 33, 35, 39, 45, 51, 52, 56, 58, 59, 66, and/or 685

I've bolded the five strains that the Gardasil 9 vaccine guards against (more on vaccines below). When I was quite young, I received the original Gardasil vaccine, which only guards against 6, 11, 16, and 18. Gardasil 9 is a newer vaccine that guards against those four as well as 31, 33, 45, 52, & 58. (Since learning I was infected, I've completed the Gardasil 9 vaccine series to broaden my protection going forward.)

Unfortunately, tests for HPV are done in clusters, so it is hard to pinpoint exactly what strain you have. From 2021–2024, I tested negative for HPV 16/18 but positive for one of the other oncogenic strains. However, in 2025, my pap came with slightly different clustering: they tested for HPV 16 separately, and then tested the cluster HPV 18 and/or HPV 45. I came back positive for that second cluster.

Given that I was vaccinated against HPV 18 (twice) and had never tested positive for it previously, this means we have most likely identified the culprit strain: HPV-45.

I'm still trying to see if I can get one of the older tests run (that cluster HPV 16/18) to confirm. And there's also always the chance that I am co-infected with an additional oncogenic strain that may or may not be covered by Gardasil 9.

Some weak additional evidence: I dated a rather sexually prolific partner for several years and have hooked up somewhat regularly with other partners in the Bay Area for several years, and I have not heard of any reports of my partners' partners becoming infected with HPV, which might be slight evidence that the Gardasil 9 vaccine (which my ex received when he started dating me and which many women and some men already have) is protective against my strain. Or maybe everyone's immune systems are stronger than mine, or maybe my metamours haven't gone in for their pap smears recently?

Transmission

HPV is highly transmissible! Mostly, it is spread via penetrative sex, but there is some concern that you can catch oral versions via oral sex or even deep kissing. However, my sense is that this is quite unlikely? Chapter 6: Epidemiology and transmission dynamics of genital HPV infection, Table 3 includes 4 studies on "Oral HPV infection associated with oral sex," and it doesn't look like any of them find a clear connection between oral sex and infection with oral HPV.6

Vaccination

HPV vaccination is recommended for everyone — the CDC recommends it for all children at age 11–12. It was originally only recommended for girls in 2006, and then in 2011 it was also recommended for boys.7 However, in my experience, doctors are much more rigorous about ensuring that women get the vaccine. So most women will have received the Gardasil or Gardasil 9 vaccine already, but many men may not have. You should check your records!

I would strongly encourage men to get the vaccine. Why not help prevent the spread of the highest risk strains and protect yourself too? If you are a man and your doctor resists, you can point them to the updated guidance, or just tell them you're poly and have a lot of sexual partners — I had one partner face this, but after learning more, the doctor was willing to give the vaccine. Note that if you're over 26, it's not always covered by insurance.

The Gardasil 9 vaccine is 3 shots spread out over several months: after your first shot, you get your second shot at month 1 or 2, and the final shot at month 6.

Testing

I'm tested for HPV each year when I go in for my pap smear, to see if it has cleared. This is usually in the summer for me. There is no routine testing for men.

There do seem to be some testing options available to men — anal pap smears and PCR skin swabs (either from urethra or penile skin) — I haven't looked into the details or reliability of these.8 It's also worth noting that some testing may not be that useful: PCR testing in particular can pick up all kinds of HPV that just hang out on your skin and aren't sexually-transmitted, which might cause unnecessary alarm without being that useful.9

How risky is sexually-transmitted HPV?

Warts

I won't focus much on this, because the type I have does not cause warts. Beyond HPV-6 and HPV-11, there are other strains that cause warts, but I've read claims that those two strains cause ~90% of genital warts.

Cancer

Cancer is the main risk from oncogenic strains like the one I have:

"Infections can also persist and cause cell abnormalities that in a small number of cases can develop into cancers. The biggest risk is to those who have cervixes, because the cervix is more susceptible to these changes. However, HPV cancers can also affect the oral region, and less commonly the penis, anus, scrotum, vagina and vulva." —r/HPV

HPV can affect the cervical region & other genital regions because of the types of cells HPV lives in:

"HPV lives in thin, flat cells called epithelial cells. These are found on the skin's surface. They're also found on the surface of the vagina, anus, vulva, cervix and head of the penis. They're also found inside the mouth and throat." —WebMD

Actually, I don't quite get this — epithelial cells are basically just skin surface cells, and they are everywhere? So why don't we see HPV-caused cancer everywhere in the body?

After reading this, a friend sent me this quote about HPV from Medical Microbiology by Ryan and Ray: "there is a predilection for infection at the junction of squamous and columnar epithelium (e.g. in the cervix and anus)." I don't really understand this, but it seems like a useful pointer if you want to dive in more.

Cervical Cancer

According to the CDC:

"About 10% of women with HPV infection on their cervix will develop long-lasting HPV infections that put them at risk for cervical cancer." —CDC — Basic Information about HPV and Cancer

Also, while it's common to catch high-risk strains of HPV, progression to cancer is rare:

"With a lifetime risk of high-risk human papillomavirus (hrHPV) infection around 80% and less than 1% of those infections leading to cervical cancer, the development of a cervical carcinoma is a rare complication of hrHPV infection." —Infection to Cancer — Finding Useful Biomarkers for Predicting Risk of Progression to Cancer

HPV-16 and HPV-18 cause about 70% of cervical cancers,10 and Gardasil 9 covers five strains that are responsible for another ~15% of cases:11

"Around 12 types of HPV are considered high risk for cancer of the cervix. Two of these types (HPV 16 and HPV 18) cause about 7 out of 10 (70%) cervical cancer cases." —Risks and Causes of Cervical Cancer
"The 9-valent HPV vaccine protects against HPV types 16 and 18, which cause about 66% of cervical cancers and most other HPV-attributable cancers in the United States, and five additional cancer-causing types, which account for about 15% of cervical cancers. It also protects against HPV 6 and 11, which cause most anogenital warts." —CDC — Administering HPV Vaccine

So, if my partner has the Gardasil 9 vaccine, they're protected from the types which cause ~85% of cervical cancer cases.

~12,000 women in the U.S. are diagnosed with cervical cancer each year, ~4,000 women die from cervical cancer each year, and there are ~170 million women in the U.S. Here's some basic math:

  1. Annual incidence rate: 12,000 / 170,000,000 = 0.0071% or 7.1 per 100,000 women
  2. Annual mortality rate: 4,000 / 170,000,000 = 0.0024% or 2.4 per 100,000 women
  3. Case fatality rate: 4,000 / 12,000 = 33.33%12

Here's a toy population model (still need to clean it up) starting with the assumption that we have 100,000 women who get cancer from high-risk strains:

Toy Population Model BOTEC13

So, if I have HPV-45 as I suspect, I think I have about a 1 in 500 chance of dying from it. The Gardasil-9 vaccine has 97% efficacy against preventing transmission.14 So assuming my partner is vaccinated and their partner is vaccinated, that means partners-of-my-partners will have a roughly 1 in 500,000 chance of dying from my strain.15

I also think this is a conservative overestimate of risk, for a few reasons. First, less than 1% of HPV infections turn into cancer (I'm not sure how much less). Second, screening regularly offers additional protection:

"Cervical cancer is considered a preventable disease. Screening reduces the mortality of this cancer by identifying and treating precancerous lesions at a lower stage. Also, performing a single cervical cancer screening test in a lifetime reduces this cancer by 25–36%."16

Screening is likely already partially reflected in my numbers, given that we're talking about the U.S. But if women are diligent about going in for their pap smear every three years (or annually if positive for HPV), I expect they'll do better than average. There's a 91% 5-year relative survival rate for cervical cancer caught early,17 and abnormal cells turn into cancer quite slowly (over 10–20 years), so I expect annual screening will put you in that early detection bucket.

(Also, death rates will likely decrease over time as we develop better detection, treatment, etc. You may put more weight on this if you think AI will have transformative impacts on medical research over the next 10–20 years.)

I basically think partners with the Gardasil-9 vaccine should not be that concerned here. I do sometimes feel scared that I have this risk of death, now that I've got this strain that's sticking around. I'm not sure if I'm already in the 10% who have "long-lasting" infections, but I have had my HPV since at least 2021, possibly longer. And even if death is unlikely, it's possible some uncomfortable treatments for pre-cancerous tissue could be in my future, if my body doesn't clear this.

I may be crunching the numbers wrong — I'm not an epidemiologist, so if you're stronger at this kind of analysis, I'd appreciate anyone double-checking my numbers. For instance, I'm not quite sure how to include (or if I need to include) the likelihood that partners may not contract my strain of HPV (let alone then pass it on to further partners), independent of vaccination status.18

Other types of cancer

For now, I've focused on cervical cancer, since it's much more common. However, this footnote has some numbers on rates of other types of cancer that HPV can cause long-term.19 I'd like to have some better numbers for "if you catch my strain of HPV, what's the chance you'd develop a different type of cancer?"

According to this source:

"HPV can cause six types of cancer: These include anal cancer, cervical cancer, oropharyngeal cancer, penile cancer, vaginal cancer, and vulvar cancer."

From that same source:

How much protection do condoms offer?

There's mixed evidence.

There have been some studies since the Manhart review that are indicative of condom impact:

I think it's probably fair to assume that condoms are moderately protective, but by no means fully protective.

Social norming

If you want to base your behavior on others' behavior, here's what I've seen so far:

Other facts that may be useful

  1. There are a bunch of different estimates, but I have seen a lot of claims like this: "More than 90 percent of sexually active men and 80 percent of sexually active women will be infected with HPV in their lifetime." (Minnesota Department of Health, Quick Facts — HPV) ↩
  2. However, there are some skin conditions that might look like warts / be colloquially referred to as warts that are not caused by HPV. For instance, Molluscum contagiosum. ↩
  3. I've read this claim, but I'm not entirely sure this is true. It does seem to be the case that nobody thinks the types listed as highest risk cause genital warts, other than HPV-6 and HPV-11. ↩
  4. "More than 200 HPV types are known to exist (Burd 2003, Unger et al 2004) with 15 types associated with cervical cancer… the high-risk or oncogenic HPV types include types 16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59, 68, 73, and 82 (Walboomers et al 1999)" Human Papillomavirus and Cervical Cancer. (I'm not sure why 66 isn't listed here even though it's listed on my Kaiser results. I think understanding of HPV continues to evolve.) ↩
  5. It seems this is a generally agreed-upon set of strains that are highest risk. E.g., according to Cancer.gov: "High-risk HPVs can cause several types of cancer. There are about 14 high-risk HPV types including HPV 16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59, 66, and 68. Two of these, HPV16 and HPV18, are responsible for most HPV-related cancers." ↩
  6. Also, it seems like the prevalence of oral HPV is less than 10% (CDC); if HPV were transmitted as easily orally as it is genitally, I would expect this to be higher? ↩
  7. Recommendations on the Use of Quadrivalent Human Papillomavirus Vaccine in Males — Advisory Committee on Immunization Practices (ACIP), 2011 ↩
  8. There is more detail on male testing in this article, and here's a resource on anal pap smears. I have not looked at these much. ↩
  9. "We also have the reality that everyone has various strains of HPV at any one time, everyone's had previous infections, and we'll probably all have future infections. I'm reminded of a post on here where a well-meaning man had PCR testing from several regions of his genitals, and it came back with a whole list of strains, most of which are probably doing nothing but just hanging out in the skin for a bit. I'm willing to bet if you PCR tested any one of us we'd probably receive a similar result. This young man was feeling dreadful, knowing he had all these infections and thinking about transmitting them to partners. But is he any different from any other guy out there? Does this information help him or his potential partners?" —r/HPV ↩
  10. I had Claude vet this report, and Claude wrote: "HPV-16 and HPV-18 coverage shows the research identifies both 66% and 70% figures. FDA documents cite 66%, while WHO and most peer-reviewed literature consistently report 70%. Both fall within the accepted range of 65–77% found in global meta-analyses, with 70% being the more authoritative figure." ↩
  11. This resource indicates those strains may be responsible for up to 20% of cancers? "The prevalence of high-risk HPV genotypes varies in cervical cancer cases. Of the 14 high-risk HPV genotypes, 16, 18, and 45 cause 77% of cervical cancers worldwide. HPV types 16, 18, 45, 33, 58, 52 and 31 contribute to 90% of all cervical cancer. HPV types 51, 35, 39, 68, 56, 59, and 66, contribute to less than 9% of all cervical cancer." ↩
  12. I looked up survival rates, and they seem to roughly match this calculation. ↩
  13. Assuming a few cases come from non-HPV causes, as indicated here and other sources. ↩
  14. Efficacy against certain HPV-related cancers and diseases in individuals aged 16–26 and Gardasil 9 Vaccine Protects against Additional HPV Types ↩
  15. Each vaccinated link in the chain reduces transmission by 97%, meaning only 3% (0.03) gets through. With two vaccinated links: 0.03 × 0.03 × 1/500 = about 1 in 555,556, or roughly 1 in 500,000 for simplicity. ↩
  16. Global, regional and national burden, incidence, and mortality of cervical cancer ↩
  17. Cervical Cancer Prognosis and Survival Rates ↩
  18. Some rough data points here: This article indicates that there's a 20% chance of catching HPV over 6 months (50% of the couples had sex without a condom and the avg amount of sex was 4x per week). This seems to be a study indicating transmission of high-risk strains (HPV 16 and 18) was closer to 80–90% per partnership; I'm unsure over what timeframe. If we assume no vaccination, and my partner has an 80% chance of catching my strain, and then their partner has an 80% chance again of catching from them, that puts risk of death at 0.8 × 0.8 × 1/500, or ~1 out of 781. (Infrequent hook-ups or condom use are going to decrease this.) If we assume all partners have a 50% chance of catching HPV, risk is ~1/2,000 from my strain. ↩
  19. "These are less common than cervical cancer. Each year in the United States, there are about: 1,500 women who get HPV-associated vulvar cancer; 500 women who get HPV-associated vaginal cancer; 400 men who get HPV-associated penile cancer; 2,700 women and 1,500 men who get HPV-associated anal cancer; 1,500 women and 5,600 men who get HPV-associated oropharyngeal cancers (cancers of the back of throat including base of tongue and tonsils). [Note: Many of these cancers may be related to tobacco and alcohol use.]" —Illinois Department of Public Health ↩
  20. "In our study, consistent condom users following treatment illustrated significantly lower probability of testing HPV positive at 6 and 24 post-op months besides having subsequently lower chances for treatment failure. Specifically, six months following recruitment, women reporting consistent condom use exhibited a 23% HPV DNA positivity rate, while women with inconsistent use presented an almost three-fold higher rate (62%); thus, a ≥90% use of condoms decreased the odds for HPV positivity (OR: 0.19, 95%CI: 0.10–0.36, p < 0.0001). Two years later, women with consistent condom use had even lower HPV DNA positivity rates (13%) while 71% of women with inconsistent use tested HPV DNA positive (OR: 0.06, 95%CI: 0.03–0.13, p < 0.000). In summary, women with consistent condom use not only had lower HPV DNA positivity rates both after 6 and 24 months, as compared to women with inconsistent condom use, but, additionally, they illustrated a decreasing trend for HPV DNA positivity rate over time (from 23% to 13%), while inconsistent users had an increasing HPV positivity rate (from 62% to 71%)." ↩
  21. "In 2019, a total of 565,541 cases of cervical cancer were reported worldwide, of which only 11% were detected in high SDI countries. The age-standardized incidence of cervical cancer in the world in 2019 was 13.35 per 100,000 women and the age-standardized mortality rate was 6.51 per 100,000 women." Source ↩
  22. "The most common HPV types detected were HPV-62 (3.3%; 95% CI, 2.2%–5.1%) and HPV-84 (3.3%; 95% CI, 2.2%–5.1%), HPV-53 (2.8%; 95% CI, 2.1%–3.7%), and HPV-89 (2.4%; 95% CI, 1.4%–4.3%) and HPV-61 (2.4%; 95% CI, 1.6%–3.8%). HPV-16 was detected in 1.5% (95% CI, 0.9%–2.6%) of females aged 14 to 59 years. There was no statistically significant difference in the prevalence of HPV-16 and the 13 more commonly detected types, except for HPV-84 and HPV-62. HPV-6 was detected in 1.3% (95% CI, 0.8%–2.3%), HPV-11 in 0.1% (95% CI, 0.03%–0.3%; relative SE≥30%), and HPV-18 in 0.8% (95% CI, 0.4%–1.5%) of female participants. Most participants infected with HPV (60.1%) had only 1 HPV type detected (95% CI, 53.2%–67.9%); however, 23.9% had 2 types (95% CI, 18.3%–31.3%) and 16% had 3 or more types detected (95% CI, 12.0%–21.2%). Overall, HPV types 6, 11, 16, or 18 were detected in 3.4% of the study participants, corresponding with 3.1 million females with prevalent infection with HPV types included in the quadrivalent HPV vaccine. Few participants (0.10%) had both HPV types 16 and 18 and none had all 4 HPV vaccine types. At least 1 of these 4 HPV types was detected in 6.2% (95% CI, 3.8%–10.3%) of females aged 14 to 19 years." Prevalence of HPV Infection Among Females in the United States ↩