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.
Gaps in identifying what is sexually transmitted
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:
- 95% Genital herpes
- 94% Gonorrhea
- 91% Syphilis
- 89% Chlamydia
- 75% HPV, a six-point increase from 2024
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:
- 92% know that HIV can be sexually transmitted.
- 35% know that mpox , also called monkeypox, can be sexually transmitted.
- 13% know that Zika or ZIKV, which is primarily mosquito-borne, can also be sexually transmitted.
"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."
Broad awareness of STI transmission but misconceptions persist
The survey shows strong awareness of common ways that STIs are transmitted:
- 97% identify vaginal sex as a transmission route
- 94% anal sex
