Fewer Symptoms for Mpox Infection Seen After Vaccination

THURSDAY, Dec. 29, 2022 (HealthDay News) -- Individuals with mpox infection ≥14 days after receipt of one JYNNEOS vaccine dose have less hospitalization, fever, headache, malaise, myalgia, and chills compared with unvaccinated individuals, according to research published in the Dec. 30 issue of the U.S. Centers for Disease Control and Prevention Morbidity and Mortality Weekly Report.

Jennifer L. Farrar, M.P.H., from the CDC Mpox Emergency Response Team, and colleagues describe the demographic and clinical characteristics of mpox cases occurring ≥14 days after receipt of one dose of the JYNNEOS vaccine and compared them to characteristics of unvaccinated persons with mpox. The analysis included 6,605 mpox cases during May 22 to Sept. 3, 2022, with available vaccination information.

The researchers found that overall, 276 cases (4.2 percent) occurred among people who had received one dose of vaccine ≥14 days before onset of illness. Mpox cases that occurred in vaccinated individuals versus unvaccinated individuals were associated with a lower percentage of hospitalization (2.1 versus 7.5 percent), fever, headache, malaise, myalgia, and chills.

"Although infection ≥14 days after receipt of one JYNNEOS vaccine dose is infrequent, the occurrence of such cases and the unknown duration of protection conferred by one vaccine dose highlights the need for providers and public health officials to encourage completion of the two-dose vaccination series among persons at risk," the authors write.

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