JYNNEOS Vaccine Effectiveness

What to know

JYNNEOS vaccine is effective. Two doses of the vaccine provide the best protection. People who get vaccinated can still get mpox, but their illness may be less severe.

Effectiveness data

JYNNEOS vaccine is effective at reducing the risk of mpox, with two doses providing the best protection.

Vaccine effectiveness (VE) measures how well vaccination works under real-world conditions to protect people against infection, symptomatic illness, hospitalization, and death. For instance, 70% VE means that the number of vaccinated people who are ill is 70% lower than the number of unvaccinated people who are ill.

Multiple studies are needed to generate reliable, real-world VE estimates. These studies show JYNNEOS can reduce the risk of mpox illness, with two doses providing the best protection. No vaccine is 100% effective. People who have been vaccinated can still get mpox, but vaccination may make illness less severe.

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Chart showing effectiveness of JYNNEOS vaccine

Adjusted vaccine effectiveness (VE) percent (95% CI) of JYNNEOS vaccine against mpox by study and number of doses.

Full (2 doses) vaccination

Multijurisdictional: 88% (74% – 92%)

New York State: 89% (44% – 98%)

Epic Cosmos: 66% (47% – 78%)

Partial (1 dose) vaccination

Multijurisdictional: 75% (61% – 84%)

New York State: 68% (25% – 87%)

Epic Cosmos: 36% (22% – 47%)

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Factors affecting vaccine efficacy estimates

These studies used different methods and data sources and also accounted for different factors that could influence VE estimates. Therefore, the estimates may not be directly comparable. However, all studies showed that the JYNNEOS vaccine is effective in preventing mpox.

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Content Source:
National Center for Emerging and Zoonotic Infectious Diseases (NCEZID)