Abstract
During May 2022-May 2023, approximately 30,000 mpox cases were reported in the United States, predominantly among young adult men. Persons aged >50 years might experience more severe mpox disease because of a higher prevalence of comorbidities. Conversely, they could have residual protection from childhood smallpox vaccination against monkeypox virus infection and severe mpox, as has been suggested by investigation of some previous mpox outbreaks. To examine the characteristics of mpox cases among adults aged >50 years, analysts compared mpox epidemiology and clinical outcomes among all adults aged ≥18 years, by age group. Further, outcomes were compared among adults aged >50 years by JYNNEOS vaccination status. During May 10, 2022-May 17, 2023, among 29,984 adults with probable or confirmed mpox reported to CDC, 2,909 (9.7%) were aged >50 years, 96.3% of whom were cisgender men. Compared with adults aged 18-50 years, adults aged >50 years had higher prevalences of immunocompromising conditions (p<0.001) and HIV infection (p<0.001). Among adults with mpox aged >50 years, 27.6% had received JYNNEOS vaccination; this group had lower prevalences of constitutional symptoms (p<0.001), pruritus (p<0.001), and hospitalization (p = 0.002) compared with those who had not received JYNNEOS vaccine. Currently recommended JYNNEOS vaccination among all adults at risk for mpox should be encouraged, irrespective of childhood smallpox vaccination status.