Vaccine Effectiveness of JYNNEOS against Mpox Disease in the United States

This nationwide case–control study evaluated the real-world effectiveness of the JYNNEOS vaccine in preventing medically attended mpox among high-risk adults. Using data from 2193 mpox patients and 8319 matched controls (new HIV diagnoses or active PrEP prescriptions), vaccine effectiveness was 66.0% (95% CI, 47.4–78.1) with full vaccination (two doses) and 35.8% (95% CI, 22.1–47.1) with partial vaccination (one dose). Effectiveness was higher among non-immunocompromised patients and those with heterologous dose administration (one intradermal, one subcutaneous). The study supports the two-dose JYNNEOS schedule for high-risk populations and underscores the need for improved vaccination coverage and follow-up among at-risk groups.

This nationwide case–control study evaluated the real-world effectiveness of the JYNNEOS vaccine in preventing medically attended mpox among high-risk adults. Using data from 2193 mpox patients and 8319 matched controls (new HIV diagnoses or active PrEP prescriptions), vaccine effectiveness was 66.0% (95% CI, 47.4–78.1) with full vaccination (two doses) and 35.8% (95% CI, 22.1–47.1) with partial vaccination (one dose). Effectiveness was higher among non-immunocompromised patients and those with heterologous dose administration (one intradermal, one subcutaneous). The study supports the two-dose JYNNEOS schedule for high-risk populations and underscores the need for improved vaccination coverage and follow-up among at-risk groups.