Two STIs have widely available, FDA-approved vaccines: hepatitis B and human papillomavirus (HPV). Hepatitis A, which can spread through sexual contact, also has an effective vaccine. Beyond these, a newer vaccine for mpox is available for people at higher risk. Other major STIs, including HIV, herpes, gonorrhea, chlamydia, and syphilis, do not yet have approved vaccines.
HPV: The Most Effective STI Vaccine
The HPV vaccine (sold as Gardasil 9) protects against nine strains of human papillomavirus, including the types responsible for roughly 81% of cervical cancers in the United States. It also prevents the strains that cause genital warts. In clinical trials, the vaccine was close to 100% effective at preventing persistent infections and precancerous changes caused by the targeted strains, as long as the person hadn’t already been infected.
The CDC recommends two doses at ages 11 to 12, though vaccination can start as early as age 9. If you start the series before your 15th birthday, you only need two doses given 6 to 12 months apart. Starting at 15 or older requires three doses. Routine vaccination is recommended through age 26. Adults between 27 and 45 who weren’t vaccinated earlier can discuss catch-up vaccination with their doctor, though the benefit decreases with age since most people have already been exposed to HPV by then.
Hepatitis B: Recommended for All Adults Under 60
Hepatitis B spreads through blood, semen, and other body fluids, making sexual contact one of the most common routes of transmission. The vaccine has been part of the childhood immunization schedule for decades, and as of 2024, the CDC recommends universal hepatitis B vaccination for all adults aged 19 to 59. Adults 60 and older with risk factors are also advised to get vaccinated.
Several vaccine options are available, including single-antigen vaccines and a combination vaccine that covers both hepatitis A and B. Most formulations require two or three doses over several months. The vaccine is highly effective at preventing chronic hepatitis B infection, which can lead to liver cirrhosis and liver cancer if left untreated.
Hepatitis A: Sexually Transmitted but Often Overlooked
Hepatitis A doesn’t always make the list when people think of STIs, but it spreads readily through sexual activity, not just through fecal-oral contact with contaminated food or water. The CDC specifically recommends hepatitis A vaccination for men who have sex with men, people who inject drugs, and anyone living with or having sex with someone who has an active hepatitis A infection.
Two inactivated vaccines are available (Havrix and VAQTA), plus the combination hepatitis A/B vaccine Twinrix. Vaccination is the single most effective way to prevent hepatitis A transmission.
Mpox: A Newer Option for Higher-Risk Groups
Mpox (formerly monkeypox) spreads through close skin-to-skin contact, including during sex. The JYNNEOS vaccine is available for adults 18 and older who are at elevated risk. After two doses, the vaccine is roughly 66% to 89% effective at preventing mpox, depending on the study. Unvaccinated people were about 9.6 times more likely to develop mpox compared to those who completed both doses. Even a single dose offers partial protection, reducing risk by about 36%.
JYNNEOS is not recommended for the general population. It’s primarily offered to men who have sex with men and others identified as being at increased risk during outbreaks.
STIs That Still Lack a Vaccine
HIV
Despite decades of research and billions of dollars invested, no HIV vaccine has proven effective enough for approval. The most recent large-scale trial, called Mosaico, was stopped in 2023 after an interim analysis showed essentially no difference in infection rates between the vaccine and placebo groups. An earlier trial, Imbokodo, showed only about 14% efficacy, far too low to be useful. Researchers are now pursuing a fundamentally different strategy: training the immune system step by step to produce broadly neutralizing antibodies. A Phase 1 trial showed this approach can activate the right immune cells in 97% of recipients, but turning that into a working vaccine is still years away.
Herpes (HSV-2)
No approved vaccine exists for genital herpes. At least 12 vaccine candidates are in various stages of development, spanning several different technologies including mRNA (the same platform behind some COVID vaccines). Several candidates showed promise in early trials but stalled. GEN-003, once considered a leading candidate, was abandoned after disappointing Phase 2 results. A few newer candidates have shown encouraging results in animal studies, but none has yet proven effective in large human trials.
Gonorrhea
There is no licensed gonorrhea vaccine. Interestingly, a meningitis B vaccine (Bexsero) has shown modest cross-protection against gonorrhea because the bacteria that cause the two infections are closely related. A large meta-analysis found that receiving at least one dose of this meningitis vaccine was about 32% effective against gonorrhea. That’s not enough for a standalone gonorrhea prevention strategy, but multiple clinical trials are currently investigating whether the meningitis vaccine could be formally recommended for gonorrhea prevention as well.
Chlamydia and Syphilis
Neither chlamydia nor syphilis has a vaccine in advanced clinical development. Both remain treatable with antibiotics, but rising infection rates, particularly for syphilis, underscore the need for additional prevention tools.
What This Means Practically
If you’re looking at a list of STIs and wondering which ones are vaccine-preventable, the clear answers are HPV and hepatitis B. Hepatitis A belongs on that list too, since sexual transmission is well documented. Mpox is the newest addition, though vaccination is targeted rather than universal. For everything else, including HIV, herpes, gonorrhea, chlamydia, and syphilis, prevention still relies on barrier methods, testing, and treatment.
The HPV vaccine in particular is one of the most effective cancer-prevention tools available. If you’re under 26 and haven’t been vaccinated, or you’re under 60 and haven’t received the hepatitis B series, both are worth discussing at your next appointment.