Healthy weeks saved by using condoms
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Waiting for inputs
- acts/partner 10 years 3 sex acts/week
Estimated healthy weeks lost Without condoms -
With condoms -
HPV vaccines reduces negative QALYs by HPV healthy-time loss -
Recent testing reduces negative QALYs by Test-covered STI loss -
Odds of at least 1 pregnancy Without condoms -
With condoms -
Projected children Without condoms -
With condoms -
Breakdown
Estimated healthy weeks lost by condition Condition Without condoms With condoms Benefit
*Not an STI/STD. Included because sex can cause pain or injury, trigger UTIs, raise BV risk a bit or lead to yeast infections after antibiotics.
Assumptions What this estimates Each STI row combines the chance a partner can pass it on, the chance it spreads over 10 years and the healthy time one infection is expected to cost. Asterisked rows are extra physical harms caused by sex. Background BV, background UTIs, unrelated antibiotic use and pregnancy health harms stay out. Totals are average expected healthy-time loss, not a prediction for one person. Pregnancy is shown separately instead of being folded into the healthy-week totals. Partners, testing, age and sex acts The college-degree checkbox is a broad stand-in for a lower-risk partner pool. Recent testing, number of recent partners, geography, age, partner network and injection-drug history can matter more. The recent-test selector assumes every partner had the widest realistic STI panel a U.S. clinician would plausibly order and a typical insured patient could expect to have at least about 90% covered: HIV blood testing, syphilis serology, chlamydia/gonorrhea NAAT at all exposed sites and genital trichomoniasis NAAT. Hepatitis B/C screens can also be covered or recommended for adults, but hepatitis rows are not part of this calculator. Insurance, coding and clinician willingness vary, so this is a broad insured-panel assumption rather than a guaranteed no-cost preventive screen. A recent negative test helps most for chlamydia/gonorrhea and trichomoniasis NAAT testing, somewhat for HIV blood testing and less for syphilis because of early-window misses. It says nothing about infections acquired after the sample was collected. Trich benefit applies only to genital testing; CDC does not recommend rectal or oral trich testing. The test selector does not move HPV, HSV, M. genitalium or Ureaplasma. HPV testing is cervical-cancer screening, not a general partner-status test; HSV-2 screening is not recommended for the general population and HSV-1 blood tests do not locate infection; asymptomatic M. genitalium screening is not recommended; and Ureaplasma testing is not recommended in routine cervicitis/urethritis workups. Partner risk is not truly independent. Ten partners from the same tested friend-of-friends network is different from ten unrelated partners from a broad national pool. Age is not included. HSV rates, HPV vaccine benefit, pregnancy risk and oral-cancer risk can change a lot by age and birth cohort. Oral and vaginal sex share one 10-year period. The default math is closer to vaginal sex, so oral-heavy sex can overstate HIV risk and misplace some oral HPV, HSV and gonorrhea risk. Pregnancy Pregnancy uses standard first-year contraceptive failure rates, spread across the 10-year horizon. Typical use: none 85%, pull out 20%, pill 7%, implant 0.1%, male condom 13%. Perfect use: pull out 4%, pill 0.3%, implant 0.1%, male condom 2%. The condom case can mean switching to condoms alone or using condoms plus the selected no-condom method. When methods are stacked, the calculator multiplies failure rates; in real life, people who miss pills may also use condoms inconsistently. Each pregnancy creates a fixed 1.25-year pause in pregnancy risk. This is just a spacing assumption. It is not a claim that breastfeeding makes someone infertile for 1.25 years. Projected children uses the expected number of pregnancies and the user-selected share of unintended pregnancies that result in a child. HPV and vaccines The HPV vaccine setting only changes HPV-related rows. The 100% setting means full protection for HPV types covered by the modeled HPV rows; the adult prior-exposure setting is a lower-benefit case, not a CDC number. The HPV-related throat-cancer row starts from lifetime risk, then shrinks it so the partner slider can move it. Real cancer risk depends on sex, age, smoking, oral-sex history, vaccination and HPV type. Existing HPV status is not tracked. If someone is already vaccinated or already exposed to a vaccine-covered HPV type, the benefit can differ from the default. HSV HSV rows use adult population rates, then remove the roughly 40% distress-after-diagnosis share. The calculator counts physical health loss, not stigma, disclosure anxiety, neonatal HSV or HIV risk caused by HSV. HSV-2 condom protection depends on which partner has HSV and which partner is exposed. Genital HSV-1 stands in for HSV-1 passed from oral sex to the genitals. HSV-1 blood tests do not tell whether infection is oral or genital, and prior HSV-1 or HSV-2 infection is not tracked. HIV The HIV row uses the chance that a partner has HIV that can spread through sex. Partners with an undetectable viral load are treated as not transmitting HIV through sex. The HIV transmission rates are CDC vaginal-sex estimates. Oral-heavy sex can make the HIV row too high. Bacterial STIs, M. genitalium and Ureaplasma Chlamydia, gonorrhea, trichomoniasis and syphilis use low-risk background rates instead of raw national case counts, because case counts depend heavily on who gets tested. M. genitalium is one of the shakier rows. Female healthy-time loss is scaled from chlamydia using PID risk. Male healthy-time loss counts urethritis only because long-term male complication data are weak. M. genitalium drug resistance, repeat treatment, lingering infection and medication side effects are not counted separately. Ureaplasma only counts possible high-load U. urealyticum urethritis in men, not ordinary Ureaplasma carriage. Female healthy-time loss is set to zero because guidelines do not support a cervicitis/PID/infertility estimate. BV, UTIs and antibiotic-associated yeast Post-sex UTIs are extra UTIs caused by sex. They are not partner rate times transmission chance and they are not all UTIs someone might otherwise get. The default assumes few sex-triggered UTIs; the UTI-prone toggle uses a higher after-sex UTI rate. Ordinary condoms stay neutral for UTIs. Sex itself is the main trigger this calculator counts; product details, lubrication, friction and individual anatomy are not split out. Yeast infections come only from antibiotic courses for post-sex UTIs and bacterial STIs acquired in this calculator. Antibiotics for unrelated illnesses stay out. The yeast-prone toggle uses the yeast-with-symptoms rate from a small antibiotic study. BV is a separate vaginal-health row for the female side only. It counts only extra BV with symptoms tied to sex, not all BV in sexually active people and not BV that can happen without sex. Condoms reduce only that extra BV row using the pooled condom-use estimate, not the stronger perfect-use estimate. Other physical sex harms Dyspareunia means pain during sex. PID not from gonorrhea/chlamydia means pelvic inflammatory disease with some other cause. Those and fissures get their own rows because the evidence is stronger and the healthy-time loss is not already covered by the STI rows. These rows count only the extra harm from sex. They do not count pain, pelvic infection or vulvar disease that would have happened anyway. Tiny base-case risks are left out: PHASA (sex headache), sex-triggered heart attack or cardiac arrest, orgasm-triggered brain bleed, heterosexual HCV, hepatitis A without oral-anal exposure, mpox outside a relevant outbreak, Zika without travel exposure, transient global amnesia, pregnancy-only air embolism and EBV/CMV. Some risks are real but too data-poor or too person-specific for a default row: POIS, semen allergy, latex/lube irritation, molluscum, scabies, pubic lice, hepatitis B edge cases, penile fracture, frenulum tears, small muscle/joint flares and rare urethritis bugs. For the default user, these are near-zero healthy-time losses or need their own toggle to avoid fake precision. Uncertainty controls The uncertainty control moves the weakest STI inputs: HPV progression, HSV physical-only healthy-time loss, bacterial STI healthy-time loss, M. genitalium and high-load Ureaplasma. These are not real confidence intervals. They are a quick way to see whether the answer changes when the weakest assumptions move up or down. Sources and anchors
Grouped roughly like the assumptions above.
Testing, oral sex and surveillance Bacterial STIs, M. genitalium and Ureaplasma BV, UTIs and antibiotic-associated yeast