Severity Reduced With Mpox Reinfection, Postvaccination Infection

MONDAY, Sept. 11, 2023 (HealthDay News) — The clinical features and outcomes of mpox reinfection and infection postvaccination are less clinically severe than initial infection, according to a global case series published online Sept. 4 in The Lancet Infectious Diseases.

Aniruddha Hazra, M.D., from the University of Chicago Medicine, and colleagues describe the epidemiological and clinical characteristics of mpox in individuals with past infection or vaccination in a global case series. Data were provided from international collaborators from nine countries on individuals with polymerase chain reaction-confirmed mpox after documented previous infection or vaccination between May 11, 2022, and June 30, 2023.

Mpox infections were reported in 37 gay and bisexual men who have sex with men: seven had mpox reinfections, 29 had infections that occurred after two vaccine courses, and one had an infection that met the criteria for both reinfection and infection after vaccination. The researchers found that compared with the initial infection, those with natural immunity after initial infection had a shorter disease course with less mucosal disease upon reinfection. Few lesions, little mucosal disease, and minimal analgesia requirements characterized infections postvaccination. Oral tecovirimat was received by two people. No deaths and no bacterial superinfections occurred, and all individuals were managed in the ambulatory clinic; one patient was admitted to the hospital for a necrotizing neck lesion.

“These findings support the literature, signaling that vaccinations might reduce duration and severity,” the authors write.

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