A Phase 3 interventional study of tecovirimat and Placebo in Smallpox, sponsored by SIGA Technologies. Completed at 11 sites in United States. Open to participants aged 18 Years to 80 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-09-11.
Sponsored by SIGA Technologies · Phase 3, Interventional, and Treatment
Multicenter, double-blind, placebo controlled, Phase 3 study to determine the safety and tolerability of oral tecovirimat, an anti orthopoxvirus compound, in subjects.
Pharmacokinetics and safety and tolerability data will be collected.
73 studies on the registry are indexed under Smallpox; 5 are open to participants now.
This study's enrollment of 449 is above the median of 150 across 61 interventional studies indexed under Smallpox.
Browse Smallpox studies →SIGA Technologies is the lead sponsor of 9 studies on the registry; none are open to participants now.
Counted across the registry records on this site, refreshed daily.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
Able to become pregnant: from the first period until menopause, unless permanently unable to through surgery (removal of the womb, or of both ovaries or both fallopian tubes).
Criteria for people of childbearing potential usually ask for a negative pregnancy test and for contraception during the study and for a time after it.
Periods have stopped for good: usually no period for 12 months in a row without another medical reason, sometimes confirmed by a blood test (FSH).
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Malignancy means cancer. Criteria about another or earlier malignancy ask whether you have had a different cancer, usually within a set number of years.
Some are commonly allowed, such as treated skin cancers other than melanoma and early cancers removed completely — check the exceptions this study lists.
A recording of the heart’s electrical activity, taken with stickers on the chest, arms and legs. It takes a few minutes and does not hurt.
Hepatitis B is a virus that infects the liver. These are separate tests: HBsAg positive usually means a current infection (a recent vaccination can briefly cause it too); total anti-HBc (HBcAb) positive means an infection now or in the past; HBV DNA measures how much virus is in the blood.
Some studies accept a past infection if HBV DNA is undetectable, sometimes with antiviral medicine during the study. Check what this study allows.
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
A weakened immune system. It can come from an illness, such as HIV or some blood cancers, or from medicines that turn the immune system down, for example after an organ transplant or for an autoimmune disease; steroids at higher doses count.
Read whether the line is about a condition or about medicines, and which medicines and doses it means.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Clinically significant
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Childbearing potential
Able to become pregnant: from the first period until menopause, unless permanently unable to through surgery (removal of the womb, or of both ovaries or both fallopian tubes).
Criteria for people of childbearing potential usually ask for a negative pregnancy test and for contraception during the study and for a time after it.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Postmenopausal
Periods have stopped for good: usually no period for 12 months in a row without another medical reason, sometimes confirmed by a blood test (FSH).
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraception
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Cancer (malignancy)
Malignancy means cancer. Criteria about another or earlier malignancy ask whether you have had a different cancer, usually within a set number of years.
Some are commonly allowed, such as treated skin cancers other than melanoma and early cancers removed completely — check the exceptions this study lists.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
ECG (electrocardiogram)
A recording of the heart’s electrical activity, taken with stickers on the chest, arms and legs. It takes a few minutes and does not hurt.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hepatitis B tests
Hepatitis B is a virus that infects the liver. These are separate tests: HBsAg positive usually means a current infection (a recent vaccination can briefly cause it too); total anti-HBc (HBcAb) positive means an infection now or in the past; HBV DNA measures how much virus is in the blood.
Some studies accept a past infection if HBV DNA is undetectable, sometimes with antiviral medicine during the study. Check what this study allows.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
HIV
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Immunosuppression
A weakened immune system. It can come from an illness, such as HIV or some blood cancers, or from medicines that turn the immune system down, for example after an organ transplant or for an autoimmune disease; steroids at higher doses count.
Read whether the line is about a condition or about medicines, and which medicines and doses it means.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
600 mg tecovirimat capsules BID to assess safety and tolerability and pharmacokinetics of the anit-orthopoxvirus compound Tecovirimat when administered orally in healthy subjects
Drug: tecovirimat
matching placebo capsules BID to assess safety and tolerability and pharmacokinetics of the anit-orthopoxvirus compound Tecovirimat when administered orally in healthy subjects
Other: Placebo
Study is based on Animal Regulatory Rule
Also known as: ST-246
Does not apply
To Determine the Number of Participants With Adverse Events
To determine the safety and tolerability of oral tecovirimat
Time frame: 45 days
| Milestone | Active | Placebo |
|---|---|---|
| Started | 359 | 90 |
| Completed | 334 | 85 |
| Not completed | 25 | 5 |
| Withdrew: Adverse event | 6 | 2 |
| Withdrew: Lost to follow-up | 6 | 1 |
| Withdrew: Protocol violation | 4 | 1 |
| Withdrew: Withdrawal by subject | 4 | 0 |
| Withdrew: Inability to complete study procedures | 5 | 1 |
To determine the safety and tolerability of oral tecovirimat
| Participants | Active | Placebo |
|---|---|---|
| To Determine the Number of Participants With Adverse Events | 134 | 30 |
Collected over Adverse event data was collected from Day 1 Randomization Visit after study drug dosing through the Day 28 Follow-up Visit. Subjects with unresolved AE/SAE at the Day 28 Follow-up Visit were required to complete a Day 45 AE/SAE only Follow up Visit. All AEs/SAEs were to be followed until the subject was no longer participating in the study, or the AE/SAE was stable or until resolution.. Non-serious events are listed at a 0% frequency threshold.
| Group | Deaths | Serious | Other |
|---|---|---|---|
| Active | — | 1/359 (0.3%) | 134/359 (37.3%) |
| Placebo | — | 0/90 (0%) | 30/90 (33.3%) |
| Event | Active | Placebo |
|---|---|---|
| Pulmonary embolus (pulmonary embolism)Respiratory, thoracic and mediastinal disorders | 1/359 | 0/90 |
| Event | Active | Placebo |
|---|---|---|
| HeadacheNervous system disorders | 61/359 | 13/90 |
| NauseaGastrointestinal disorders | 20/359 | 5/90 |
| FatigueGeneral disorders | 5/359 | 4/90 |
| DiarrhoeaGastrointestinal disorders | 11/359 | 3/90 |
| DizzinessNervous system disorders | 9/359 | 3/90 |
| VomitingGastrointestinal disorders | 9/359 | 0/90 |
| ConstipationGastrointestinal disorders | 5/359 | 2/90 |
| SomnolenceNervous system disorders | 2/359 | 2/90 |
| Back painMusculoskeletal and connective tissue disorders | 1/359 | 2/90 |
| Oropharyngeal painSkin and subcutaneous tissue disorders | 1/359 | 2/90 |
| Age, Continuous(years) | Active | Placebo | Total |
|---|---|---|---|
| Mean | 40.4 ± 15.67 | 41.9 ± 15.85 | 40.7 ± 15.70 |
| Sex: Female, Male(Participants) | Active | Placebo | Total |
|---|---|---|---|
| Female | 211 | 54 | 265 |
| Male | 148 | 36 | 184 |
| Ethnicity (NIH/OMB)(Participants) | Active | Placebo | Total |
|---|---|---|---|
| Hispanic or Latino | 43 | 5 | 48 |
| Not Hispanic or Latino | 315 | 85 | 400 |
| Unknown or Not Reported | 1 | 0 | 1 |
| Race (NIH/OMB)(Participants) | Active | Placebo | Total |
|---|---|---|---|
| American Indian or Alaska Native | 3 | 0 | 3 |
| Asian | 3 | 1 | 4 |
| Native Hawaiian or Other Pacific Islander | 1 | 1 | 2 |
| Black or African American | 101 | 26 | 127 |
| White | 249 | 62 | 311 |
| More than one race | 0 | 0 | 0 |
| Unknown or Not Reported | 2 | 0 | 2 |
| Region of Enrollment(participants) | Active | Placebo | Total |
|---|---|---|---|
| United States | 359 | 90 | 449 |
Plan to share: Undecided
This study is completed, as verified in Oct 2017. You cannot join it, but the record below documents what was studied.
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Studies of the drug tested here: Tecovirimat
SIGA Technologies