While data from the Centers for Disease Control and Prevention (CDC) show that the total number of U.S. cases of three sexually transmitted infections (STIs) declined from 2022-24, infection rates remain 13% higher than a decade ago. CDC provisional data show more than 2.2 million U.S. cases of chlamydia, gonorrhea, and syphilis were reported in 2024.
Now, a nationally representative survey of empaneled adults from the Annenberg Public Policy Center (APPC) of the University of Pennsylvania finds that while most Americans understand how STIs spread, there are significant gaps in public knowledge about which infections can be prevented through vaccination.
In the Annenberg survey, conducted April 14-28, 2026, among 1,639 U.S. adults, nearly half of the respondents (47%) say that they or someone they know has ever been diagnosed with an STI. Most of those (72%) who know someone with an STI report knowing two or more people with it. (Download the topline .)
CDC data show how common these infections are. The CDC says the most common STI is human papillomavirus or HPV, and about 85% of people will get an HPV infection in their lifetime. The CDC also has estimated that on any given day in 2018, about 20% of the U.S. population – 1 in 5 people – had an STI.
A sexually transmitted infection, the CDC says , is “a virus, bacteria, fungus or parasite people can get through sexual contact.” There are dozens of STIs. Some are spread mainly by sexual contact (such as genital herpes, gonorrhea, syphilis, chlamydia, and HPV). Some are sometimes spread by sexual transmission (HIV (human immunodeficiency virus), mpox). And some can be spread sexually but are more often spread in other ways (Zika).
The survey finds that a large majority of respondents know that infections which spread mainly by sexual contact are sexually transmitted. In most cases, there has been no significant change in public knowledge from 2024 to 2026. The percentages who know that these diseases are sexually transmitted are:
Although sexual transmission is just one of several ways that HIV can be spread, Americans are much more aware that it can be sexually transmitted than they are about mpox or Zika:
“Public understanding improves when accurate health information reaches people clearly and consistently,” said Ken Winneg, APPC’s managing director of survey research. “But these findings show continuing gaps in awareness about diseases which can be sexually transmitted such as HPV, mpox, and Zika.”
The survey shows strong awareness of common ways that STIs are transmitted:
In addition, 49% selected kissing, which is not a common route for STI transmission but may be a form of transmission of syphilis when a sore is present and may be a risk factor for oral gonorrhea . And 1 in 5 (20%) chose sitting on a toilet after someone with an STI sat on it. CDC guidance for a number of STIs ( HIV , syphilis , and genital herpes , for instance) says that sitting on a toilet seat is not a form of transmission.
Public understanding is uneven around less common transmission pathways for HIV, in particular. While 92% recognize HIV as sexually transmitted, only 33% know it also can be transmitted by breastfeeding. According to the CDC , HIV can be transmitted during pregnancy, childbirth, or breastfeeding.
The public’s awareness of which diseases can be prevented with vaccines varies widely. For most of the diseases in our survey, a substantial part of the population says it does not know whether there is a vaccine for them. For the two diseases which may be prevented by vaccines:
For some other infections, most Americans are unaware that no vaccine exists:
The survey highlights the public’s strong knowledge of some basic facts about STIs:
“HPV vaccination is important for preventing cancers caused by HPV,” said Laura A. Gibson , an APPC research analyst. “The increase in awareness that HPV is sexually transmitted is a positive development, but it is concerning to see a similar increase in the incorrect belief that the HPV vaccine leads teens to engage in risky sexual behavior.”
The survey findings come as syphilis continues to pose a major public health challenge in the United States. According to the CDC’s latest provisional surveillance data , there were more than 190,000 reported syphilis cases in 2024, and the national syphilis rate reached 55.9 cases per 100,000 people. While overall syphilis cases declined about 9% from 2023 levels, congenital syphilis — when the infection is passed from a pregnant person to a baby — increased for the 12th consecutive year, with nearly 4,000 reported cases in 2024. The CDC reports congenital syphilis rates are now nearly 700% higher than a decade ago.
The current survey suggests that many Americans remain uncertain about how syphilis can be prevented and treated. Over 9 out of 10 people (91%) correctly identify syphilis as sexually transmitted but more than half of U.S. adults (61%) are either unsure whether there is a vaccine against syphilis (44%) or say a vaccine exists (17%). It does not, according to the Mayo Clinic .
“Too many Americans remain uncertain about basic facts surrounding syphilis, including how it is prevented and treated,” said Patrick E. Jamieson , director of the policy center’s Annenberg Health and Risk Communication Institute, which oversees the survey. “Those knowledge gaps can have serious public health consequences.”
About 4 in 5 respondents know how to protect against getting syphilis: 80% correctly identify abstinence and 78% correctly identify condom use as ways to protect against syphilis.
The CDC recommends regular STI screening, condom use, prompt antibiotic treatment, and prenatal testing during pregnancy to reduce transmission and prevent congenital syphilis.
Three bacterial infections – gonorrhea , chlamydia , and syphilis – can be cured with appropriate antibiotics, according to the CDC, but you can be re-infected. Three viral STIs – HPV, genital herpes, and HIV – cannot be cured. Although HPV cannot be cured, in 9 out of 10 cases, “ HPV goes away on its own within two years without health problems,” the CDC says. When HPV does not resolve, it can cause cervical and other cancers. Genital herpes is a lifelong infection and has no cure, according to the CDC, but there are medicines that can “prevent or shorten outbreaks.” HIV has no cure but can be managed with medication.
Most patients with mpox who are not severely immunocompromised “will recover with supportive care and pain control only,” the CDC says . Zika has no specific cure but typically resolves on its own, although in rare cases it can cause severe disease affecting the brain.
The findings come from Wave 29 of the Annenberg Science and Public Health survey (ASAPH), conducted April 14-28, 2026, among 1,639 U.S. adults. It was conducted for the policy center by SSRS , an independent research company. The nationally representative probability-based panel, which was first empaneled in April 2021, has a margin of sampling error of ± 3.5 percentage points at the 95% confidence level. All figures are rounded to the nearest whole number and may not add to 100%. Combined subcategories may not add to totals in the topline and text due to rounding.
Download the topline and methodology report.
The policy center has been tracking the American public’s knowledge, beliefs, and behaviors regarding vaccination, Covid-19, flu, RSV, and other consequential health issues through the Annenberg Science and Public Health (ASAPH) survey and separate national samples since April 2021. The ASAPH survey is conducted under the auspices of APPC’s Annenberg Health and Risk Communication Institute (AHRCI) by a team that includes Ken Winneg, managing director of survey research; research analysts Laura A. Gibson and Shawn Patterson Jr.; and Patrick E. Jamieson, director of the Annenberg Health and Risk Communication Institute.
See other recent Annenberg health survey news releases:
The Annenberg Public Policy Center was established in 1993 to educate the public and policy makers about communication’s role in advancing public understanding of political, science, and health issues at the local, state, and federal levels.
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