Trial Outcomes & Findings for Tecovirimat for Treatment of Monkeypox Virus (NCT NCT05559099)

Last Updated: 2025-10-09

Results Overview

Number of days from randomization to the first day on which all lesions on the total body are scabbed or desquamated or a new layer of epidermis has formed.

Recruitment status

COMPLETED

Study phase

PHASE2

Target enrollment

597 participants

Primary outcome timeframe

Up to day 28

Results posted on

2025-10-09

Participant Flow

Patients were recruited from the areas surrounding two sites in rural Democratic Republic of the Congo - Tunda and Kole. Patient recruitment took place from October 2022 through July 9, 2024.

Participant milestones

Participant milestones
Measure	Tecovirimat Tecovirimat capsules administered orally to participants for 14 days plus SOC.	Placebo Matching placebo capsules administered orally to participants for 14 days plus SOC.
Overall Study STARTED	295	302
Overall Study COMPLETED	289	295
Overall Study NOT COMPLETED	6	7

Reasons for withdrawal

Reasons for withdrawal
Measure	Tecovirimat Tecovirimat capsules administered orally to participants for 14 days plus SOC.	Placebo Matching placebo capsules administered orally to participants for 14 days plus SOC.
Overall Study Death	5	4
Overall Study Lost to Follow-up	0	2
Overall Study Adverse Event	1	1

Baseline Characteristics

Race and Ethnicity were not collected from any participant.

Baseline characteristics by cohort

Baseline characteristics by cohort
Measure	Tecovirimat n=295 Participants Tecovirimat capsules administered orally to participants for 14 days plus SOC.	Placebo n=302 Participants Matching placebo capsules administered orally to participants for 14 days plus SOC.	Total n=597 Participants Total of all reporting groups
Age, Continuous	16.4 Years STANDARD_DEVIATION 13.9 • n=295 Participants	15.3 Years STANDARD_DEVIATION 13.9 • n=302 Participants	15.8 Years STANDARD_DEVIATION 13.9 • n=597 Participants
Sex: Female, Male Female	141 Participants n=295 Participants	151 Participants n=302 Participants	292 Participants n=597 Participants
Sex: Female, Male Male	154 Participants n=295 Participants	151 Participants n=302 Participants	305 Participants n=597 Participants
Race and Ethnicity Not Collected	—	—	0 Participants Race and Ethnicity were not collected from any participant.
Days since onset of symptoms	5.9 Days STANDARD_DEVIATION 2.5 • n=295 Participants	5.9 Days STANDARD_DEVIATION 2.8 • n=302 Participants	5.9 Days STANDARD_DEVIATION 2.6 • n=597 Participants
Less than or equal to 7 days since onset of symptoms	234 Participants n=295 Participants	239 Participants n=302 Participants	473 Participants n=597 Participants
Greater than 7 days since onset of symptoms	61 Participants n=295 Participants	63 Participants n=302 Participants	124 Participants n=597 Participants

PRIMARY outcome

Timeframe: Up to day 28

Population: Intention to treat population

Number of days from randomization to the first day on which all lesions on the total body are scabbed or desquamated or a new layer of epidermis has formed.

Outcome measures

Outcome measures
Measure	Tecovirimat n=295 Participants Tecovirimat capsules administered orally to participants for 14 days plus SOC.	Placebo n=302 Participants Matching placebo capsules administered orally to participants for 14 days plus SOC.
Time to Lesion Resolution	7 Days Interval 7.0 to 8.0	8 Days Interval 7.0 to 9.0

SECONDARY outcome

Timeframe: up to day 28

Population: Intention to treat population - participants with symptom onset less than or equal to 7 days before randomization

Number of days to the first day on which all lesions on the total body are scabbed or desquamated or a new layer of epidermis has formed.

Outcome measures

Outcome measures
Measure	Tecovirimat n=234 Participants Tecovirimat capsules administered orally to participants for 14 days plus SOC.	Placebo n=239 Participants Matching placebo capsules administered orally to participants for 14 days plus SOC.
Time to Lesion Resolution for Participants With Symptom Onset Less Than or Equal to 7 Days Before Randomization	7 Days Interval 7.0 to 8.0	8 Days Interval 7.0 to 8.0

SECONDARY outcome

Timeframe: up to day 28

Population: Intention to treat population - participants with symptom onset greater than 7 days before randomization

Number of days to the first day on which all lesions on the total body are scabbed or desquamated or a new layer of epidermis has formed.

Outcome measures

Outcome measures
Measure	Tecovirimat n=61 Participants Tecovirimat capsules administered orally to participants for 14 days plus SOC.	Placebo n=63 Participants Matching placebo capsules administered orally to participants for 14 days plus SOC.
Time to Lesion Resolution for Participants With Symptom Onset Greater Than 7 Days Before Randomization	8 Days Interval 7.0 to 10.0	8 Days Interval 7.0 to 11.0

SECONDARY outcome

Timeframe: day 14

Population: Intention to treat population - participants with positive MPXV PCR in the blood at baseline

Percentage of participants with negative blood sample MPXV PCR results 14 days post-randomization, out of those positive at baseline

Outcome measures

Outcome measures
Measure	Tecovirimat n=160 Participants Tecovirimat capsules administered orally to participants for 14 days plus SOC.	Placebo n=162 Participants Matching placebo capsules administered orally to participants for 14 days plus SOC.
Number and Percentage of Participants With Negative Blood PCR Results	140 Participants	141 Participants

SECONDARY outcome

Timeframe: day 14

Population: Intention to treat population - participants with positive oropharyngeal swab MPXV PCR results at baseline

Number and percentage of participants with negative oropharyngeal swab MPXV PCR results 14 days post-randomization, out of those positive at baseline

Outcome measures

Outcome measures
Measure	Tecovirimat n=260 Participants Tecovirimat capsules administered orally to participants for 14 days plus SOC.	Placebo n=259 Participants Matching placebo capsules administered orally to participants for 14 days plus SOC.
Number and Percentage of Participants With Negative Oropharyngeal Swab PCR Results	144 Participants	136 Participants

SECONDARY outcome

Timeframe: day 14

Population: Intention to treat population - participants with positive lesion swab MPXV PCR results at baseline

Number and and percentage of participants with negative lesion swab MPXV PCR results 14 days post-randomization, of those positive at baseline

Outcome measures

Outcome measures
Measure	Tecovirimat n=280 Participants Tecovirimat capsules administered orally to participants for 14 days plus SOC.	Placebo n=291 Participants Matching placebo capsules administered orally to participants for 14 days plus SOC.
Number and Percentage of Participants With Negative Lesion Swab PCR Results	256 Participants	259 Participants

SECONDARY outcome

Timeframe: up to day 28

Population: Intention to treat population

Number of deaths post-randomization

Outcome measures

Outcome measures
Measure	Tecovirimat n=295 Participants Tecovirimat capsules administered orally to participants for 14 days plus SOC.	Placebo n=302 Participants Matching placebo capsules administered orally to participants for 14 days plus SOC.
Mortality Within the First 28 Days Post-randomization	3 Participants	4 Participants

SECONDARY outcome

Timeframe: Up to day 14

Population: As-treated population

Number of participants with a non-fatal serious adverse event requiring permanent drug discontinuation through the end of the treatment period (14 days)

Outcome measures

Outcome measures
Measure	Tecovirimat n=295 Participants Tecovirimat capsules administered orally to participants for 14 days plus SOC.	Placebo n=302 Participants Matching placebo capsules administered orally to participants for 14 days plus SOC.
Incidence of Non-fatal Serious Adverse Events Requiring Permanent Drug Discontinuation	0 Participants	2 Participants

SECONDARY outcome

Timeframe: Up to day 14

Population: As-treated population

Number of participants with a non-fatal adverse event requiring permanent drug discontinuation through the end of the treatment period (14 days)

Outcome measures

Outcome measures
Measure	Tecovirimat n=295 Participants Tecovirimat capsules administered orally to participants for 14 days plus SOC.	Placebo n=302 Participants Matching placebo capsules administered orally to participants for 14 days plus SOC.
Incidence of Non-fatal Adverse Events Requiring Permanent Drug Discontinuation	1 Participants	0 Participants

SECONDARY outcome

Timeframe: up to day 28

Population: As-treated population

Number of participants with an adverse event up to day 28

Outcome measures

Outcome measures
Measure	Tecovirimat n=295 Participants Tecovirimat capsules administered orally to participants for 14 days plus SOC.	Placebo n=302 Participants Matching placebo capsules administered orally to participants for 14 days plus SOC.
Incidence of Adverse Events	196 Participants	199 Participants

SECONDARY outcome

Timeframe: up to day 28

Population: As-treated population

Number of participants with a bacterial infection adverse event up to day 28

Outcome measures

Outcome measures
Measure	Tecovirimat n=295 Participants Tecovirimat capsules administered orally to participants for 14 days plus SOC.	Placebo n=302 Participants Matching placebo capsules administered orally to participants for 14 days plus SOC.
Incidence of Bacterial Infection Adverse Events	23 Participants	27 Participants

Adverse Events

Tecovirimat

Serious events: 15 serious events

Other events: 214 other events

Deaths: 5 deaths

Placebo

Serious events: 15 serious events

Other events: 211 other events

Deaths: 5 deaths

Serious adverse events

Other adverse events

Other adverse events
Measure	Tecovirimat n=295 participants at risk Tecovirimat capsules administered orally to participants for 14 days plus SOC.	Placebo n=302 participants at risk Matching placebo capsules administered orally to participants for 14 days plus SOC.
Blood and lymphatic system disorders Anaemia	5.4% 16/295 • Number of events 16 • From enrollment until the end of follow-up, up to 58 days All adverse events were documented and recorded and all grade 3 and above adverse events were reported to a study pharmacovigilance committee from the time informed consent was obtained through the end of subject participation in the study. Where possible, adverse events were graded according to the "Common Terminology Criteria for Adverse Events (CTCAE) version 5.0. Laboratory values or events not included in CTCAE were graded using tables provided in the study protocol.	6.3% 19/302 • Number of events 19 • From enrollment until the end of follow-up, up to 58 days All adverse events were documented and recorded and all grade 3 and above adverse events were reported to a study pharmacovigilance committee from the time informed consent was obtained through the end of subject participation in the study. Where possible, adverse events were graded according to the "Common Terminology Criteria for Adverse Events (CTCAE) version 5.0. Laboratory values or events not included in CTCAE were graded using tables provided in the study protocol.
Gastrointestinal disorders Abdominal pain	10.5% 31/295 • Number of events 32 • From enrollment until the end of follow-up, up to 58 days All adverse events were documented and recorded and all grade 3 and above adverse events were reported to a study pharmacovigilance committee from the time informed consent was obtained through the end of subject participation in the study. Where possible, adverse events were graded according to the "Common Terminology Criteria for Adverse Events (CTCAE) version 5.0. Laboratory values or events not included in CTCAE were graded using tables provided in the study protocol.	8.6% 26/302 • Number of events 26 • From enrollment until the end of follow-up, up to 58 days All adverse events were documented and recorded and all grade 3 and above adverse events were reported to a study pharmacovigilance committee from the time informed consent was obtained through the end of subject participation in the study. Where possible, adverse events were graded according to the "Common Terminology Criteria for Adverse Events (CTCAE) version 5.0. Laboratory values or events not included in CTCAE were graded using tables provided in the study protocol.
General disorders Pyrexia	13.2% 39/295 • Number of events 40 • From enrollment until the end of follow-up, up to 58 days All adverse events were documented and recorded and all grade 3 and above adverse events were reported to a study pharmacovigilance committee from the time informed consent was obtained through the end of subject participation in the study. Where possible, adverse events were graded according to the "Common Terminology Criteria for Adverse Events (CTCAE) version 5.0. Laboratory values or events not included in CTCAE were graded using tables provided in the study protocol.	14.2% 43/302 • Number of events 47 • From enrollment until the end of follow-up, up to 58 days All adverse events were documented and recorded and all grade 3 and above adverse events were reported to a study pharmacovigilance committee from the time informed consent was obtained through the end of subject participation in the study. Where possible, adverse events were graded according to the "Common Terminology Criteria for Adverse Events (CTCAE) version 5.0. Laboratory values or events not included in CTCAE were graded using tables provided in the study protocol.
Infections and infestations Malaria	11.5% 34/295 • Number of events 35 • From enrollment until the end of follow-up, up to 58 days All adverse events were documented and recorded and all grade 3 and above adverse events were reported to a study pharmacovigilance committee from the time informed consent was obtained through the end of subject participation in the study. Where possible, adverse events were graded according to the "Common Terminology Criteria for Adverse Events (CTCAE) version 5.0. Laboratory values or events not included in CTCAE were graded using tables provided in the study protocol.	17.9% 54/302 • Number of events 55 • From enrollment until the end of follow-up, up to 58 days All adverse events were documented and recorded and all grade 3 and above adverse events were reported to a study pharmacovigilance committee from the time informed consent was obtained through the end of subject participation in the study. Where possible, adverse events were graded according to the "Common Terminology Criteria for Adverse Events (CTCAE) version 5.0. Laboratory values or events not included in CTCAE were graded using tables provided in the study protocol.
Investigations Haemoglobin decreased	5.1% 15/295 • Number of events 15 • From enrollment until the end of follow-up, up to 58 days All adverse events were documented and recorded and all grade 3 and above adverse events were reported to a study pharmacovigilance committee from the time informed consent was obtained through the end of subject participation in the study. Where possible, adverse events were graded according to the "Common Terminology Criteria for Adverse Events (CTCAE) version 5.0. Laboratory values or events not included in CTCAE were graded using tables provided in the study protocol.	6.0% 18/302 • Number of events 18 • From enrollment until the end of follow-up, up to 58 days All adverse events were documented and recorded and all grade 3 and above adverse events were reported to a study pharmacovigilance committee from the time informed consent was obtained through the end of subject participation in the study. Where possible, adverse events were graded according to the "Common Terminology Criteria for Adverse Events (CTCAE) version 5.0. Laboratory values or events not included in CTCAE were graded using tables provided in the study protocol.
Metabolism and nutrition disorders Decreased appetite	6.8% 20/295 • Number of events 20 • From enrollment until the end of follow-up, up to 58 days All adverse events were documented and recorded and all grade 3 and above adverse events were reported to a study pharmacovigilance committee from the time informed consent was obtained through the end of subject participation in the study. Where possible, adverse events were graded according to the "Common Terminology Criteria for Adverse Events (CTCAE) version 5.0. Laboratory values or events not included in CTCAE were graded using tables provided in the study protocol.	4.6% 14/302 • Number of events 14 • From enrollment until the end of follow-up, up to 58 days All adverse events were documented and recorded and all grade 3 and above adverse events were reported to a study pharmacovigilance committee from the time informed consent was obtained through the end of subject participation in the study. Where possible, adverse events were graded according to the "Common Terminology Criteria for Adverse Events (CTCAE) version 5.0. Laboratory values or events not included in CTCAE were graded using tables provided in the study protocol.
Nervous system disorders Headache	6.8% 20/295 • Number of events 20 • From enrollment until the end of follow-up, up to 58 days All adverse events were documented and recorded and all grade 3 and above adverse events were reported to a study pharmacovigilance committee from the time informed consent was obtained through the end of subject participation in the study. Where possible, adverse events were graded according to the "Common Terminology Criteria for Adverse Events (CTCAE) version 5.0. Laboratory values or events not included in CTCAE were graded using tables provided in the study protocol.	9.3% 28/302 • Number of events 28 • From enrollment until the end of follow-up, up to 58 days All adverse events were documented and recorded and all grade 3 and above adverse events were reported to a study pharmacovigilance committee from the time informed consent was obtained through the end of subject participation in the study. Where possible, adverse events were graded according to the "Common Terminology Criteria for Adverse Events (CTCAE) version 5.0. Laboratory values or events not included in CTCAE were graded using tables provided in the study protocol.
Respiratory, thoracic and mediastinal disorders Cough	11.2% 33/295 • Number of events 33 • From enrollment until the end of follow-up, up to 58 days All adverse events were documented and recorded and all grade 3 and above adverse events were reported to a study pharmacovigilance committee from the time informed consent was obtained through the end of subject participation in the study. Where possible, adverse events were graded according to the "Common Terminology Criteria for Adverse Events (CTCAE) version 5.0. Laboratory values or events not included in CTCAE were graded using tables provided in the study protocol.	9.9% 30/302 • Number of events 32 • From enrollment until the end of follow-up, up to 58 days All adverse events were documented and recorded and all grade 3 and above adverse events were reported to a study pharmacovigilance committee from the time informed consent was obtained through the end of subject participation in the study. Where possible, adverse events were graded according to the "Common Terminology Criteria for Adverse Events (CTCAE) version 5.0. Laboratory values or events not included in CTCAE were graded using tables provided in the study protocol.
Respiratory, thoracic and mediastinal disorders Nasal congestion	6.1% 18/295 • Number of events 18 • From enrollment until the end of follow-up, up to 58 days All adverse events were documented and recorded and all grade 3 and above adverse events were reported to a study pharmacovigilance committee from the time informed consent was obtained through the end of subject participation in the study. Where possible, adverse events were graded according to the "Common Terminology Criteria for Adverse Events (CTCAE) version 5.0. Laboratory values or events not included in CTCAE were graded using tables provided in the study protocol.	8.9% 27/302 • Number of events 27 • From enrollment until the end of follow-up, up to 58 days All adverse events were documented and recorded and all grade 3 and above adverse events were reported to a study pharmacovigilance committee from the time informed consent was obtained through the end of subject participation in the study. Where possible, adverse events were graded according to the "Common Terminology Criteria for Adverse Events (CTCAE) version 5.0. Laboratory values or events not included in CTCAE were graded using tables provided in the study protocol.
Skin and subcutaneous tissue disorders Pruritus	4.7% 14/295 • Number of events 15 • From enrollment until the end of follow-up, up to 58 days All adverse events were documented and recorded and all grade 3 and above adverse events were reported to a study pharmacovigilance committee from the time informed consent was obtained through the end of subject participation in the study. Where possible, adverse events were graded according to the "Common Terminology Criteria for Adverse Events (CTCAE) version 5.0. Laboratory values or events not included in CTCAE were graded using tables provided in the study protocol.	6.0% 18/302 • Number of events 19 • From enrollment until the end of follow-up, up to 58 days All adverse events were documented and recorded and all grade 3 and above adverse events were reported to a study pharmacovigilance committee from the time informed consent was obtained through the end of subject participation in the study. Where possible, adverse events were graded according to the "Common Terminology Criteria for Adverse Events (CTCAE) version 5.0. Laboratory values or events not included in CTCAE were graded using tables provided in the study protocol.
Skin and subcutaneous tissue disorders Skin lesion	4.4% 13/295 • Number of events 13 • From enrollment until the end of follow-up, up to 58 days All adverse events were documented and recorded and all grade 3 and above adverse events were reported to a study pharmacovigilance committee from the time informed consent was obtained through the end of subject participation in the study. Where possible, adverse events were graded according to the "Common Terminology Criteria for Adverse Events (CTCAE) version 5.0. Laboratory values or events not included in CTCAE were graded using tables provided in the study protocol.	5.3% 16/302 • Number of events 18 • From enrollment until the end of follow-up, up to 58 days All adverse events were documented and recorded and all grade 3 and above adverse events were reported to a study pharmacovigilance committee from the time informed consent was obtained through the end of subject participation in the study. Where possible, adverse events were graded according to the "Common Terminology Criteria for Adverse Events (CTCAE) version 5.0. Laboratory values or events not included in CTCAE were graded using tables provided in the study protocol.

Additional Information

Lori Dodd

National Institute of Allergy and Infectious Diseases

Phone: 2406695247

Email: [email protected]

Results disclosure agreements

Principal investigator is a sponsor employee
Publication restrictions are in place