Exposed to Mpox? Check Your Vaccine Timing

Fast. The CDC recommends the mpox vaccine (JYNNEOS) as soon as possible, ideally within 4 days of exposure — that's the window where it can help prevent the disease from developing at all. Given between 4 and 14 days after exposure, it may no longer prevent mpox but may still reduce how severe it is. After about 14 days it isn't given for that exposure, and the focus shifts to watching for symptoms. Because the window is short, don't wait for a routine appointment: contact a healthcare provider or your local health department right away and say you had a possible mpox exposure.

It's JYNNEOS, the two-dose mpox (and smallpox) vaccine. Using it after a known or likely exposure is a strategy public-health experts call post-exposure prophylaxis (PEP) — giving the vaccine quickly, before symptoms start, so your immune system can respond before the virus takes hold. The same vaccine is also used routinely, before any exposure, for people at ongoing risk; who's advised to get it that way is a separate question covered on our vaccines guide. This tool is only about responding to an exposure you think already happened.

Once symptoms have started, the vaccine is no longer the tool for you — it's meant for people who were exposed but aren't yet sick. A new rash, sores, or blisters, or fever and swollen lymph nodes after a possible exposure, mean it's time to be evaluated and tested, not vaccinated. Contact a healthcare provider or your local health department today, describe the exposure, and until you're seen, cover any sores, avoid close skin-to-skin and sexual contact, and don't share bedding, towels, or clothing. If it is mpox, there are treatment options a clinician can discuss.

The highest-risk exposures are close skin-to-skin or sexual contact with someone who has mpox — or an unexplained new rash — because mpox spreads mainly through direct contact with the rash, sores, and scabs, and through sex. Sharing a household, bed, towels, or clothing with someone who has mpox can also transmit it. Brief or indirect contact is generally lower risk, though not zero. If you're unsure whether your contact counts, that uncertainty is itself a good reason to ask a provider or health department, who can weigh the details and the timing.

Watch for a new rash — spots, pimple- or blister-like sores, or scabs — which can appear anywhere, including the genitals, anus, mouth, hands, and face, and may be painful or itchy. Other signs are fever, chills, headache, muscle aches, exhaustion, and swollen lymph nodes, which sometimes come before the rash. Symptoms can start anytime from about 3 to 21 days after exposure, so keep watching across that whole window. If anything appears, isolate, avoid close and sexual contact, and contact a provider or health department to get tested.

Completely. This tool runs entirely in your browser: your answers are never sent to a server, saved, or shared. Close the tab and they're gone. It's educational and can't diagnose you, prescribe, or give you a vaccine — only a clinician or health department can decide whether post-exposure vaccination is right for you and provide it.