A5418:Study of Tecovirimat for Human Monkeypox Virus (STOMP)

Open and enrolling

A5418:Study of Tecovirimat for Human Monkeypox Virus (STOMP)

Treatment Category


Study Description

A5418 (STOMP) is a study of tecovirimat (also known as TPOXX) for the treatment of human monkeypox virus (HMPXV) disease.

Study Purpose

  • To see if tecovirimat is safe, and whether it helps treat monkeypox infection.

Target Participant

People with:

  • Laboratory-confirmed or presumptive monkeypox infection
  • Monkeypox illness of less than 14 days’ duration
  • At least one active (not yet scabbed) skin lesion, mouth lesion, or proctitis (inflammation of the lining of the rectum) with or without visible ulcers

Study Details

Participants will be randomly assigned (like flipping a coin) in a 2:1 ratio to receive tecovirimat OR placebo for tecovirimat for 14 days.

People who are at higher risk for severe disease because of their age or their medical history will be assigned to receive open-label tecovirimat for 14 days.

All participants will be followed through a combination of in-person visits, specimen collection, virtual assessments, and self-reports and photographs of symptoms for about 2 months.

Treatments Or Drugs Involved With Study

Tecovirimat is a drug that may help to treat infections caused by pox viruses. Tecovirimat is approved by the Food and Drug Administration (FDA) to treat smallpox in adults and children, but its use in this study is considered investigational.