JYNNEOS Vaccine

General Information

  • JYNNEOS vaccine is approved for prevention of smallpox and monkeypox. It is the primary vaccine being used in the U.S. during this outbreak.
  • The JYNNEOS vaccine is given as a two-dose series. The two doses should be given 28 days apart.
  • CDC recommends getting both doses of JYNNEOS vaccine. The level of protection provided by only one dose is not known.
  • CDC recommends getting your second dose on time. But, if you are unable to, get it as soon as you can, preferably within 35 days after the first dose.
  • You are considered vaccinated against monkeypox 14 days after you receive your second vaccine dose.
  • Learn more about how vaccines work and get more technical information on JYNNEOS.
People Who Should Not Get Vaccinated

You should not get JYNNEOS vaccine if you had a severe allergic reaction after a previous dose of JYNNEOS. Talk to your healthcare provider if you have a history of an allergic reaction to the antibiotics gentamicin or ciprofloxacin, or chicken or egg protein.

Vaccine Effectiveness

  • While we expect the vaccines currently being used to help protect against monkeypox will be effective, we have not previously had an outbreak of monkeypox like the current outbreak.
  • Animal and clinical studies showed a similar immune response to both JYNNEOS vaccine and ACAM2000 vaccine.
  • To better understand the benefits and risks of these vaccines in the current monkeypox outbreak, CDC is working with its partners to collect data on vaccine safety and vaccine effectiveness.
  • We will know more in the coming months about how effective the JYNNEOS vaccine is in the 2022 monkeypox outbreak. In the meantime, people who are vaccinated are encouraged to continue to take steps to protect themselves.
  • Learn more about how vaccines work.

Long-Term Protection

  • We do not know how long protection might last, or if protection might decrease over time.
  • CDC is currently working on studies to learn more about the JYNNEOS vaccine’s effectiveness. We will use the results of these studies to make any future vaccine recommendations, including whether booster shots may be needed.
Monkeypox Vaccine Locator
Use the locator to find nearby healthcare locations providing monkeypox vaccines.

Find Vaccines

What to Expect When You Get the Vaccine

  • Like any vaccination, you will likely have to fill out paperwork before you get your vaccine.
  • The vaccine may be given in three ways:
    • If you are 18 years or older, you may be given the vaccine into the skin layers of your forearm (like a tuberculosis skin test).
    • If you are younger than 18 years or have a history of developing keloid scars, you may be given the vaccine in your upper arm, like other vaccines you may have received (like the measles, mumps, rubella (MMR) shot).
    • For infants under 12 months old, it can be given in the thigh like other vaccines they may have received (like the measles, mumps, rubella (MMR) shot).

Simultaneous Immunizations

  • In most cases, you can get a JYNNEOS vaccine at the same time you get other vaccinations, except possibly COVID-19 vaccine.
  • COVID-19 vaccines may be delayed by 4 weeks if the JYNNEOS vaccine is given first.

Side Effects

  • Not everyone experiences side effects.
  • The most common side effects after JYNNEOS vaccination are redness and itching at the spot where the vaccine is given as well as headache, tiredness, nausea, chills, and muscle aches.
  • When JYNNEOS vaccine is given into the skin of the forearm, some people have reported prolonged swelling and redness at the injection site.

Adverse Events