In September 2022, NIAID will start a clinical trial of tecovirimat in the U.S. in collaboration with the AIDS Clinical Trials Group (ACTG). People with monkeypox infection, including people living with HIV, would be eligible and encouraged to enroll. More than 500 volunteer participants will be randomly assigned to receive either tecovirimat or a placebo at a ratio of two to one. Investigators will be evaluating if those taking tecovirimat heal more quickly than those taking placebo, among other data points. There is an additional segment of the study open to pregnant and breastfeeding people and children and all will receive tecovirimat and will be closely monitored for safety. If a positive signal is seen in the study, it will provide the necessary data to make this medicine readily available for treatment of monkeypox disease.