The therapeutic efficacies of smallpox vaccine ACAM2000 and antiviral 
tecovirimat given alone or in combination starting on day 3 postinfection were 
compared in a cynomolgus macaque model of lethal monkeypox virus infection. 
Postexposure administration of ACAM2000 alone did not provide any protection 
against severe monkeypox disease or mortality. In contrast, postexposure 
treatment with tecovirimat alone or in combination with ACAM2000 provided full 
protection. Additionally, tecovirimat treatment delayed until day 4, 5, or 6 
postinfection was 83% (days 4 and 5) or 50% (day 6) effective.