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Volume 31, Number 10—October 2025

Research

Prolonged Monkeypox Virus Infections, California, USA, May 2022–August 2024

Samuel SchildhauerComments to Author , Kayla Saadeh, Robert E. Snyder, Eric C. Tang, Eric Chapman, Deanna A. Sykes, Philip Peters, Kathleen Jacobson, Jessica Watson, and Kelly A. Johnson
Author affiliation: University of California School of Medicine, Davis, California (S. Schildhauer); California Department of Public Health, Richmond, California, USA (S. Schildhauer, K. Saadeh, E.C. Tang, K. Jacobson, J. Watson, K.A. Johnson); California Department of Public Health, Sacramento, California, USA (R.E. Snyder, E. Chapman, D.A. Sykes, P. Peters); University of California, San Francisco, California, USA (K.A. Johnson)

Main Article

Table 2

Clinical characteristics of 6,469 patients with prolonged and nonprolonged monkeypox virus infections, California, USA, May 12, 2022–August 31, 2024

Characteristic Prolonged
Nonprolonged
Total
No. % (95% CI) No. % (95% CI) No. % (95% CI)
Hospitalization
Yes* 21 25.6 (16.6–36.44) 285 4.5 (3.98–5.0) 306 4.7 (4.24–5.27)
No* 49 59.8 (48.34–70.44) 4,889 76.5 (75.49–77.57) 4,938 76.3 (75.28–77.35)
Unknown
 12
 14.6 (7.8–24.17)
1,213
 19.0 (18.05–19.97)
1,225
 18.9 (18–19.91)
JYNNEOS vaccination status
Unvaccinated 76 92.7 (84.75–97.27) 5,458 85.5 (84.57–86.3) 5,534 85.5 (84.67–86.38)
1-dose vaccinated 2 2.4 (0.3–8.53) 287 4.5 (4.01–5.03) 289 4.5 (3.99–5.0)
Postexposure vaccinated 4 4.9 (1.34–12.02) 562 8.8 (8.13–9.52) 566 8.7 (8.09–9.46)
2-dose vaccinated
 0
 0.0 (0.0–4.4)
80
 1.3 (1.01–1.56)
80
 1.2 (0.99–1.54)
HIV status
HIV-positive* 50 61.0 (49.57–71.56) 2,549 39.9 (38.71–41.12) 2,599 40.2 (38.99–41.38)
HIV-negative*
 32
 39.0 (28.44–50.43)
3,838
 60.1 (58.88–61.29)
3,870
 59.8 (58.62–61.01)
Mean symptom severity score (95% CI)
 3.51 (3.3–3.72)
3.28 (3.26–3.31)
3.29 (3.27–3.31)
Total 82 6,387 6,469

*Indicates nonoverlapping 95% CIs (statistical significance).

Main Article

Page created: August 18, 2025
Page updated: September 25, 2025
Page reviewed: September 25, 2025
The conclusions, findings, and opinions expressed by authors contributing to this journal do not necessarily reflect the official position of the U.S. Department of Health and Human Services, the Public Health Service, the Centers for Disease Control and Prevention, or the authors' affiliated institutions. Use of trade names is for identification only and does not imply endorsement by any of the groups named above.
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