A Phase 3 interventional study of Molnupiravir and Placebo in Coronavirus Disease (COVID-19), sponsored by Merck Sharp & Dohme LLC. Recruiting at 229 sites in 24 countries. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-11-06.
Sponsored by Merck Sharp & Dohme LLC (part of Merck & Co., Inc) · Phase 3, Interventional, and Treatment
Researchers are looking for other ways to prevent severe illness from COVID-19. COVID-19 is a virus that most often causes mild flu or cold-like symptoms. However, people with certain health conditions or other factors have a high risk (chance) of getting severely ill from COVID-19, which can require a hospital stay or lead to death. Some people who are high risk for severe illness may be unable to take certain treatments for COVID-19 because they are not available to them, or they take other medicines that may react with a treatment and cause an unwanted effect.
Molnupiravir (MK-4482) is a study medicine designed to stop the COVID-19 virus from copying itself in the body (multiplying). The goal of this study is to learn if molnupiravir prevents severe illness from COVID-19 more than placebo in people who are high risk.
7,990 studies on the registry are indexed under COVID-19; 466 are open to participants now.
This study's planned enrollment of 3,082 is above the median of 102 across 4,364 interventional studies indexed under COVID-19.
Browse COVID-19 studies →Merck Sharp & Dohme LLC is the lead sponsor of 2,166 studies on the registry; 132 are open to participants now.
Of its 501 completed or terminated interventional studies of FDA-regulated products, 370 (74%) have results posted.
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.
The main inclusion criteria include but are not limited to the following:
Has ≥1 of the following characteristics or medical conditions associated with the highest risk of severe illness from COVID-19:
Is unable or unwilling to receive treatment with nirmatrelvir/ritonavir (NMV/r) due to 1 or more of the following:
Inclusion note: Participants may receive remdesivir as standard of care in addition to molnupiravir or placebo. If remdesivir is available and clinically appropriate per local clinical practice, investigators will aim to ensure that those who are most vulnerable to severe COVID-19 receive timely access to remdesivir as standard of care on this study.
Exclusion Criteria
The main exclusion criteria include but are not limited to the following:
Has ≥1 of the following signs/symptoms that are attributable to severe or critical COVID-19:
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.
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.
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
CYP3A is a group of enzymes, mainly CYP3A4, in the liver and gut that break down many medicines. Some medicines, supplements and foods (grapefruit, St John’s wort) slow them down or speed them up, which changes how much of a study drug stays in the body.
Studies list them so they can be avoided or switched; bring a list of everything you take, including supplements.
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.
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.
An allergy, or another reaction of the immune system, to a substance. “Hypersensitivity to the study drug” means a known allergic reaction to it — not every side effect a medicine can have.
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.
BMI (body mass index)
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
CYP3A (CYP3A4) inhibitors and inducers
CYP3A is a group of enzymes, mainly CYP3A4, in the liver and gut that break down many medicines. Some medicines, supplements and foods (grapefruit, St John’s wort) slow them down or speed them up, which changes how much of a study drug stays in the body.
Studies list them so they can be avoided or switched; bring a list of everything you take, including supplements.
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.
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.
Hypersensitivity
An allergy, or another reaction of the immune system, to a substance. “Hypersensitivity to the study drug” means a known allergic reaction to it — not every side effect a medicine can have.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Participants will receive 800 mg molnupiravir orally every 12 hours for 5 days (a total of 10 consecutive doses)
Drug: Molnupiravir
Participants will receive molnupiravir-matching placebo orally every 12 hours for 5 days (a total of 10 consecutive doses)
Drug: Placebo
Molnupiravir administered orally as two 400 mg film-coated tablets every 12 hours for 5 days (a total of 10 consecutive doses)
Also known as: MK-4482, LAGEVRIO®
Molnupiravir-matching placebo administered orally as two film-coated tablets every 12 hours for 5 days (a total of 10 consecutive doses)
Percentage of Participants Who Experienced One or More of Following Through Day 29: All-cause Hospitalization, All-cause Mortality, or Covid-19-related Medically-attended Visit (MAV)
Hospitalization is defined as ≥24 hours of acute care in a hospital or similar acute care facility, including emergency rooms or facilities created to address hospitalization needs specifically for COVID-19. Hospitalization and death may be due to any cause. An MAV is defined as any unscheduled, nonroutine healthcare visit where the participant is evaluated by a licensed (according to local/national guidelines) healthcare provider. As prespecified by the protocol, the percentage of participants who experience ONE OR MORE of these 3 events (hospitalization, death, or COVID-19-related MAV) occurring from randomization through Day 29 will be presented.
Time frame: Up to 29 days
Percentage of Participants Who Experienced an Adverse Event (AE)
An AE is any untoward medical occurrence in a clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. The percentage of participants with at least 1 AE will be presented.
Time frame: Up to approximately 5 months
Percentage of Participants Who Discontinued Study Intervention Due to AE
An AE is any untoward medical occurrence in a clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. The percentage of participants who discontinue study intervention due to an AE will be presented.
Time frame: Up to approximately 5 days
Time to Sustained Alleviation (without relapse) of all selected 8 (5 prespecified and 3 determined by baseline prevalence), self-reported COVID-19 signs/symptoms
Time to sustained alleviation without relapse is defined as the number of days from randomization to the first of 2 consecutive days when alleviation (lessening of symptoms) is demonstrated, collectively, for all 8 selected COVID-19-related sign/symptoms. Participants who experience sustained alleviation for 2 consecutive days must not relapse in any of the 8 signs/symptoms before Day 29. The time to sustained alleviation without relapse of all 8 selected COVID-19-related signs/symptoms from randomization through Day 29 will be presented.
Time frame: Up to 29 days
Change from Baseline in Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) RNA Titer
SARS-CoV-2 RNA titer (viral load) will be measured by quantitative reverse transcriptase polymerase chain reaction (RT-PCR) of samples from nasopharyngeal (NP) swabs, and the mean change from baseline will be presented.
Time frame: Day 1 (baseline) and up to Day 29
Percentage of Participants with Undetectable SARS-CoV-2 RNA
SARS-CoV-2 RNA (viral load) will be measured by quantitative RT-PCR of samples from NP swabs, and the percentage of participants with undetectable (i.e., below the lower limit of quantification) SARS-CoV-2 RNA (viral load) will be presented.
Time frame: Up to 29 days
Percentage of Participants Who Experienced One or More of Following Through Day 29: All-cause Hospitalization or All-cause Mortality
Hospitalization is defined as ≥24 hours of acute care in a hospital or similar acute care facility, including emergency rooms or facilities created to address hospitalization needs specifically for COVID-19. Hospitalization and death may be due to any cause. As prespecified by the protocol, the percentage of participants who experience hospitalization AND/OR death occurring from randomization through Day 29 will be presented.
Time frame: Up to 29 days
Percentage of Participants With Clinically Important Medical Interventions (CIMI) Associated with COVID-19-related MAV or COVID-19-related Hospitalization Through Day 29
CIMIs were prespecified by the protocol and include, but are not limited to, supplemental oxygen therapy, IV fluid administration, and nebulizer treatment. An MAV is defined as any unscheduled, nonroutine healthcare visit where the participant is evaluated by a licensed (according to local/national guidelines) healthcare provider. Hospitalization is defined as ≥24 hours of acute care in a hospital or similar acute care facility, including emergency rooms or facilities created to address hospitalization needs specifically for COVID-19. The percentage of participants with CIMIs associated with a COVID-19-related MAV AND/OR a COVID-19-related hospitalization through Day 29 will be reported.
Time frame: Up to 29 days
Time to Sustained Alleviation (without relapse) of all 15 self-reported COVID-19 signs/symptoms through Day 29
Time to sustained alleviation without relapse is defined as the number of days from randomization to the first of 2 consecutive days when alleviation (lessening of symptoms) is demonstrated, collectively, for all 15 COVID-19-related sign/symptoms. Participants who experience sustained alleviation after 2 consecutive days must not relapse in any of the 15 signs/symptoms before Day 29. The time to sustained alleviation without relapse of all 15 COVID-19-related signs/symptoms from randomization through Day 29 will be presented.
Time frame: Up to 29 days
Time to Sustained Resolution Without Relapse of all 8 (5 prespecified and 3 determined by baseline prevalence) self-reported COVID-19 signs/symptoms through Day 29
Time to sustained resolution without relapse is defined as the number of days from randomization to the first of 2 consecutive days when resolution (having no symptoms or only mild symptoms) is demonstrated, collectively, for all 8 selected COVID-19-related sign/symptoms. Participants who experience sustained resolution after 2 consecutive days must not relapse in any of the 8 signs/symptoms before Day 29. The time to sustained resolution without relapse of all 8 selected COVID-19-related signs/symptoms from randomization through Day 29 will be presented.
Time frame: Up to 29 days
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Showing the first 100 of 229 sites across 24 countries. Choose a country and city above to see the rest.
Plan to share: Yes — https://trialstransparency.msdclinicaltrials.com/pdf/ProcedureAccessClinicalTrialData.pdf
Data sharing details ↗ · externaldatasharing-msd.com
Started Dec 2024 (actual). Primary completion is estimated for Jan 2031, 73 months after the start.
Of 168 industry-sponsored phase 3 interventional studies under COVID-19, half reached primary completion within 8 months of starting (the median), counting those still running; a quarter within 4 and three quarters within 16. This study's planned 73 months is above that.
Counting every sponsor, half of 453 studies reached it within 9 months; a quarter within 4 and three quarters within 17.
How these figures are worked out, and which studies are left out of them.
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
Eligibility is decided by the study team. Share this record with your doctor or contact the team directly.
Contact study teamGet an email when the registry record changes — status, dates, results — or when someone posts here.
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Studies of the drug tested here: Molnupiravir