Mpox in People With Human Immunodeficiency Virus: Predictors of Diagnosis, Outcomes, and Vaccine Effectiveness in a Multisite Cohort.

INTRODUCTION: Since its global reemergence in 2022, monkeypox (mpox) has demonstrated increased incidence and severity among people with human immunodeficiency virus (HIV [PWH]). Predictors of mpox diagnosis, vaccination, and outcomes among PWH are limited. METHODS: We included PWH with primary care visits after 1 January 2022 at 9 US sites participating in the Centers for AIDS Research Network of Integrated Clinic Systems Network. We identified mpox diagnosed between 1 June 2022 and 31 May 2023, through a combination of polymerase chain reaction result, diagnosis code, and/or tecovirimat receipt. We examined validated clinical diagnoses, laboratory results, vaccine data, and patient reported outcomes. We evaluated relative risks (RR) of mpox diagnosis, hospitalization, tecovirimat treatment, and vaccine receipt. FINDINGS: Among 19 777 PWH in care, 413 mpox cases (all male sex at birth) occurred (2.2 cases/100 person-years). Age <40 years, geographic region, Hispanic/Latine ethnicity, lack of antiretroviral therapy, detectable HIV viral load, and recent bacterial sexually transmitted infection predicted mpox diagnosis. PWH with CD4 200-349 cells/mm3 were most likely to be hospitalized (adjusted RR, 3.20; 95% confidence interval: 1.44-7.09) compared to CD4 ≥500, but half as likely as those with CD4 <200 to receive tecovirimat. Overall, smallpox/mpox vaccine effectiveness of ≥1 vaccine was 71% (adjusted RR, 0.29; 95% confidence interval: .14-.47) at preventing mpox, and 86% or better with CD4 ≥350 or HIV viral suppression. Non-Hispanic Black PWH were less likely to be vaccinated than other racial/ethnic identities. INTERPRETATION: PWH not on antiretroviral therapy or with unsuppressed HIV were more likely to be diagnosed with, and hospitalized for, mpox. Mpox/smallpox vaccine effectiveness was high, inclusive of those with low CD4 count and HIV viremia.