The Mpox Vaccine — Who Should Get JYNNEOS

Who should get the mpox vaccine?

Public health guidance recommends the mpox vaccine for people whose recent sexual activity puts them at higher risk of exposure. In practice that most often means gay, bisexual, and other men who have sex with men, and transgender people, who in the past several months have had a new diagnosis of a sexually transmitted infection, more than one partner, or sex at a venue or event where mpox is spreading — along with the sexual partners of anyone in those groups. People whose work brings them into contact with the virus, such as certain laboratory staff, may also be advised to get it.

Eligibility is not a judgment about who you are; it is about exposure risk. Anyone who thinks they may qualify can ask a clinician or a sexual-health or public-health clinic, which can confirm current local eligibility — the criteria have widened over time and can differ by location. The vaccine is given whether or not you have ever had mpox before.

How the two-dose JYNNEOS series works

JYNNEOS is a two-dose vaccine: the second dose is given about four weeks after the first, and the strongest protection builds roughly two weeks after that second dose. Both doses matter — one dose offers some protection, but the series is designed around two, and skipping the second leaves protection incomplete. The shot is given under the skin or, in some programs, as a smaller injection into the top layers of the skin; a clinician decides which based on current guidance.

If your risk continues, the protection from completing the series is meant to last, and boosters are only advised in specific higher-exposure situations. Because mpox can still occur after vaccination, though usually more mildly, the vaccine is one layer of protection rather than a guarantee — the same way condoms, testing, and other tools each cover part of the picture.

Where the mpox vaccine fits among STI vaccines

Vaccines are the most durable form of STI prevention, and mpox joins a short list of sexually transmitted or sexually associated infections you can prevent with a shot. The other two big ones are HPV and hepatitis B. Only a few STIs are vaccine-preventable — which is exactly why the mpox vaccine matters for the people it is offered to. Knowing which STIs have a vaccine helps you see where mpox fits.

• HPV. The HPV vaccine is routinely recommended around ages 11-12 (it can start at 9), with catch-up through age 26 and shared decision-making for some adults 27 to 45 1Ref 1Centers for Disease Control and Prevention (Advisory Committee on Immunization Practices) (2024).ACIP Recommendations: Human Papillomavirus (HPV) Vaccine.HPV vaccination is routinely recommended at ages 11-12 (can start at 9), with catch-up through age 26 and shared clinical decision-making for some adults 27-45.. It prevents the virus behind most cervical and several other cancers.
• Hepatitis B. Hepatitis B, which can be transmitted sexually, is vaccine-preventable; since 2022 the CDC has recommended the vaccine for all adults aged 19 to 59, not just those with named risk factors 2Ref 2Weng MK, Doshani M, Khan MA, et al. (Centers for Disease Control and Prevention) (2022).Universal Hepatitis B Vaccination in Adults Aged 19-59 Years: Updated Recommendations of the Advisory Committee on Immunization Practices - United States, 2022.Since 2022, ACIP recommends universal hepatitis B vaccination for all adults aged 19-59 years, removing the prior risk-factor assessment requirement in that age group..

Mpox, HPV, and hepatitis B are the vaccine-preventable end of sexual-health protection; most other STIs are prevented by barriers, medication, and testing.

Vaccines are one layer — the rest of the toolkit

A vaccine covers the infection it targets, so prevention that actually works layers several tools together. For someone eligible for the mpox vaccine, the same visit is often a chance to line up the rest. Doxy-PEP — a single dose of the antibiotic doxycycline taken within 72 hours after sex — is recommended for gay and bisexual men and transgender women who have had a bacterial STI in the past year, to lower their chance of syphilis, chlamydia, and gonorrhea, with STI testing every three to six months 3Ref 3Bachmann LH, Barbee LA, Chan P, et al. (Centers for Disease Control and Prevention) (2024).CDC Clinical Guidelines on the Use of Doxycycline Postexposure Prophylaxis for Bacterial Sexually Transmitted Infection Prevention, United States, 2024.The CDC recommends counseling and offering doxy-PEP — doxycycline taken within 72 hours after sex — to gay and bisexual men and transgender women who had a bacterial STI in the prior 12 months, to prevent syphilis, chlamydia, and gonorrhea, with STI testing every 3-6 months..

Two more layers round it out. For HIV, post-exposure prophylaxis (PEP) can prevent infection if started as soon as possible and within 72 hours of a possible exposure, taken for 28 days 4Ref 4Centers for Disease Control and Prevention (2025).Antiretroviral Postexposure Prophylaxis After Sexual, Injection Drug Use, or Other Nonoccupational Exposure to HIV - CDC Recommendations, United States, 2025.HIV PEP should start as soon as possible and within 72 hours after a possible exposure and is taken for a 28-day course.. And routine STI screening — the intervals depend on your age, sex, and partners — catches infections early, including the many that cause no symptoms 5Ref 5Centers for Disease Control and Prevention (2021).STI Screening Recommendations.The CDC recommends routine STI screening at intervals that depend on age, sex, and partners, catching infections that often cause no symptoms.. None of these replace the others; together they cover far more than any one does alone.

Can you get the vaccine after an exposure?

Yes — the mpox vaccine is also used after a known or likely exposure, not only before one. When given soon after contact with someone who has mpox, it may prevent illness or make it milder, and the earlier it is given the better it tends to work. Public health programs generally aim to start it within a few days of the exposure. If you think you were exposed, a clinician or health department can tell you whether post-exposure vaccination makes sense for you and how quickly to act.

This is different from treatment. The vaccine is about preventing infection or blunting it; if mpox has already taken hold, care focuses on symptoms and, in more severe cases, specific antiviral options a clinician manages. Knowing how mpox is treated, and what mpox lesions look like, helps you tell prevention from an active infection that needs care.

Why prevention is worth it

STIs remain common in the U.S. — more than 2.4 million cases of chlamydia, gonorrhea, and syphilis were reported in 2023, with nearly half among people aged 15 to 24 6Ref 6Centers for Disease Control and Prevention (2025).National Overview of STIs in 2023.More than 2.4 million cases of chlamydia, gonorrhea, and syphilis were reported in the U.S. in 2023, with nearly half among people aged 15-24.. Mpox is far rarer than those, but it can cause painful lesions and, in some people, serious illness, and it spreads readily through the close skin-to-skin contact of sex. For the groups it is offered to, the vaccine is a low-effort way to take one more infection largely off the table.

The practical takeaway is simple. If you fall into an eligible group, the mpox vaccine is worth raising at your next sexual-health visit, where you can also update HPV and hepatitis B protection, discuss doxy-PEP or PEP if they fit, and set a testing rhythm. Prevention works best assembled — not as a single shot, but as a set of habits and layers.