Mpox after Vaccination

Two doses of JYNNEOS vaccine work to prevent mpox in most people. No vaccine is 100% effective, so in rare cases (less than 1 percent), people who have been fully vaccinated with both doses do get mpox. If someone who got both doses of the mpox vaccine does get mpox, infections are usually much milder.

What We Know

• CDC recommends vaccination for those who are at risk of mpox.
• Getting both recommended doses of the mpox vaccine makes getting and spreading mpox less likely.
• Infections after any vaccination are possible. No vaccine is 100% effective.
• If you have a rash or other symptoms of mpox, you should get tested even if you have been vaccinated or had mpox.
• The vaccine may help protect you against severe infection, hospitalization, and death.
• Research shows that whether you got the vaccine between the top layers of the skin of your forearm, shoulder blade, or high on your shoulder (intradermal vaccination), or in the fat layer in the back of your upper arm (subcutaneously), the vaccine provides good protection from mpox.
• Right now, getting more than 2 mpox vaccine doses, like a booster dose, isn’t recommended unless you work with monkeypox virus or other orthopoxviruses in a research laboratory.
• Studies are showing that people who had more sexual partners were more likely to get mpox after getting both doses of the vaccine. It may be that more chances to get mpox may increase your risk, even if you’re fully vaccinated.

What We Don’t Know

• Why some people have gotten mpox after vaccination.
• Evidence suggests that the vaccine continues to be effective and a booster is not needed, but we don’t know how long the vaccine will protect against mpox.

What We Are Doing to Find Out

• CDC and partners are studying how long mpox vaccination protects people from getting mpox.
• CDC works closely with our local and state partners to find out:
  • How the virus spreads.
  • How many people are vaccinated, if they are fully vaccinated, and when they were vaccinated.
• CDC monitors reports of people newly diagnosed with mpox after receiving two doses of the vaccine.