Mpox Vaccination Basics

Mpox (formerly known as monkeypox) is caused by a virus that is related to the virus that causes smallpox. JYNNEOS is a 2-dose vaccine developed to protect against mpox and smallpox infections. People need to get both doses of the vaccine for the best protection against mpox. The second dose should be given 4 weeks after the first dose.

Vaccination is an important tool in stopping the spread of mpox. People who are vaccinated should continue to avoid close, skin-to-skin contact with someone who has mpox.

CDC Mpox Vaccination Guidelines

• ACIP recommends vaccination^* with the 2-dose^§ JYNNEOS vaccine series for persons aged 18 years and older at risk for mpox^¶

  *This is an interim recommendation that ACIP will revisit in 2-3 years

  ^§Dose 2 administered 28 days after dose 1

  ^¶Persons at risk:

• Gay, bisexual, and other men who have sex with men, transgender or nonbinary people who in the past 6 months have had one of the following:
  • A new diagnosis of ≥1 sexually transmitted disease
  • More than one sex partner
  • Sex at a commercial sex venue
  • Sex in association with a large public event in a geographic area where mpox transmission is occurring
• Sexual partners of persons with the risks described in above
• Persons who anticipate experiencing any of the above

You should NOT get the vaccine if:

You had a severe allergic reaction (such as anaphylaxis) after getting your first dose of the JYNNEOS vaccine.

You should take extra caution if:

You had an allergic reaction to any vaccine. You may still be vaccinated with JYNNEOS, but your provider may need to observe you for 30 minutes after you get vaccinated to make sure you don’t develop an allergic reaction.

Talk to your healthcare provider if you had an allergic reaction to antibiotics, or chicken or egg protein.

How the vaccine is given

• The vaccine will be given between the top layers of your skin; this is called an intradermal vaccination. It can be placed in your forearm or other areas, including your upper back just below the shoulder blade or the skin of your shoulder above the deltoid muscle.
• If preferred, you can also ask for the vaccine to be given to you “subcutaneously.” This means that the vaccine will be injected in the fat layer underneath the skin on the back of your upper arm (triceps).
• If you have ever had keloid scars (thick, raised scars) or are under 18, ask for the vaccine to be given to you subcutaneously.
• Getting the vaccine intradermally or subcutaneously appears to be equally effective against mpox.

Although early findings suggest that the first dose of JYNNEOS vaccine gives some protection against mpox, two doses are recommended to provide stronger protection. Whether you get the vaccine subcutaneously or intradermally, you should still get two doses. The second dose should be given 4 weeks (28 days) after the first dose. If you can’t get your second dose on time, you should get it as soon as possible to complete the series.

If you don’t want the vaccine given in the skin of your forearm, ask to get it in the skin of your upper back or the skin of your shoulder instead. You can also ask to be given the vaccine subcutaneously in the fat layer underneath the skin on the back of your upper arm.

Side effects

Not everyone has side effects, but some people do. The most common side effects after JYNNEOS vaccination are pain, redness, and itching at the spot where the vaccine is given. You might also experience fever, headache, tiredness, nausea, chills, and muscle aches. These are signs that your immune system is responding, not that you’re getting sick.

When JYNNEOS vaccine is given intradermally, some people have reported less pain after vaccination but more side effects like itching, swelling, redness, thickening of the skin, and skin discoloration at the spot where the vaccine was given. Some of these side effects may last for several weeks. If you have concerns about receiving the vaccine intradermally, you can ask for the vaccine to be given to you subcutaneously in the fat layer underneath the skin on the back of your upper arm (triceps).

How long it takes for the vaccine to work

You can start to have an immune response after the first dose of JYNNEOS, but it takes two weeks after the second dose to be the most protected.

It’s not known how long protection might last, or if protection might decrease over time. CDC is analyzing the current data and conducting studies to enhance the knowledge on how well the JYNNEOS vaccine works during the current mpox outbreak, as well as how long protection might last. These studies will be used to make future vaccine recommendations.

Vaccine cost

• Mpox vaccines are free for eligible individuals through the Vaccines for Children (VFC) and Vaccines for Adults (VFA) programs. Providers must give you the vaccine regardless of your ability to pay the administration fee.
• The providers may bill a program or health insurance plan that covers the mpox vaccine administration fee (like your private insurance or Medicare/Medicaid).

Where you can get vaccinated