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A study testing molnupiravir in adults with COVID-19 who are not hospitalized and are at high risk for serious illness

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What is this trial about?

A plain-language summary of the goals, design and what participants do

This study is looking at a condition called SARS-CoV-2 (COVID-19) infection in adults who are not in the hospital but are at high risk for becoming seriously ill from the infection. The treatment being tested is molnupiravir, also known by its code name MK-4482, which is given as tablets taken by mouth. Some people in the study will receive molnupiravir while others will receive placebo tablets that look the same but contain no active medicine. The purpose of the study is to find out if molnupiravir works to prevent serious outcomes from COVID-19 and to check if it is safe for people to use.

People taking part in this study must have tested positive for the virus that causes COVID-19 within four days before joining and must have symptoms like cough, sore throat, fever, muscle aches, or other common signs of the infection. They also need to have certain health conditions or characteristics that put them at higher risk for severe illness, such as being 75 years or older, having a weakened immune system, or having multiple health problems like diabetes or lung disease. Additionally, participants must be unable or unwilling to take another COVID-19 treatment called nirmatrelvir with ritonavir for various reasons, such as taking other medicines that would interact badly with it or having certain liver problems.

During the study, participants will take either molnupiravir or placebo tablets for five days, with a maximum daily dose of 1600 milligrams. The study will track whether participants need to go to the hospital, experience death, or need medical care related to COVID-19 over a period of 29 days. The study will also monitor how quickly symptoms improve, measure the amount of virus in the body over time, and watch for any unwanted side effects that occur during treatment. This information will help researchers understand whether molnupiravir is helpful and safe for people with COVID-19 who are at high risk for serious illness.

The research process

The trial runs in 7 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Randomization and Treatment Assignment

    Upon joining the study, you will be randomly assigned to receive either molnupiravir or a placebo. A placebo is an inactive tablet that looks identical to the actual medication but contains no active ingredient.

    Neither you nor the study doctor will know which treatment you are receiving. This is called a double-blind study design.

    This randomization occurs within 4 days of your positive test result for SARS-CoV-2 and within 4 days of your initial symptoms.

  2. Step 2

    Taking the Study Medication

    You will receive molnupiravir tablets or matching placebo tablets to take by mouth.

    The specific dosage, frequency, and duration of treatment will be provided to you by the study staff according to the study protocol.

    You should follow the instructions given to you regarding when and how to take the tablets.

  3. Step 3

    Daily Symptom Monitoring

    You will be asked to monitor and report your COVID-19 symptoms on a daily basis.

    The symptoms being tracked include: cough, sore throat, nasal congestion, shortness of breath or difficulty breathing with exertion, muscle or body aches, fatigue, fever or chills, nausea, vomiting, or diarrhea, change in sense of smell or taste, and headache.

    You will need to report when these symptoms improve or resolve completely.

  4. Step 4

    Laboratory Sample Collection

    At designated time points during the study, samples will be collected to measure the amount of SARS-CoV-2 RNA in your body. RNA is the genetic material of the virus, and measuring it helps determine how much virus is present.

    These samples will help assess whether the study medication is reducing the virus level in your body.

  5. Step 5

    Safety Monitoring

    Throughout the study, you will be monitored for any adverse events. An adverse event is any unwanted medical occurrence or side effect that happens during the study.

    You should report any new symptoms, health problems, or changes in how you feel to the study staff.

    If you experience side effects that are concerning, the study doctor may decide to stop your treatment with the study medication.

  6. Step 6

    Monitoring for Serious Health Events Through Day 29

    The study will track whether you experience any of the following events up to Day 29 after starting the study: hospitalization for any reason, death from any cause, or a COVID-19-related medical visit where you needed to see a healthcare provider.

    A COVID-19-related medical visit means any visit to a doctor, clinic, or emergency room because of complications or worsening of your COVID-19 infection.

    If you require hospitalization or medical intervention related to COVID-19, this information will be recorded as part of the study.

  7. Step 7

    Follow-up Period

    You will be followed for a period extending through Day 29 from the time you were assigned to a treatment group.

    During this time, the study will continue to collect information about your symptoms, health status, and any medical care you may have needed.

    The study is expected to continue until April 2031, though your individual participation will be shorter.

Who can join the trial?

5 criteria

  • You must be 18 years of age or older
  • You must have a confirmed SARS-CoV-2 infection, which is the virus that causes COVID-19, with the test sample collected no more than 4 days before joining the study
  • Your COVID-19 symptoms must have started no more than 4 days before joining the study, and you must have at least 2 of the following symptoms on the day you join: cough, sore throat, stuffy nose, shortness of breath or trouble breathing during activity, muscle or body aches, tiredness, fever above 38.0 degrees Celsius or chills, nausea or vomiting or diarrhea, loss of smell or loss of taste, or headache
  • You must have at least one of the following high-risk conditions: you are 75 years of age or older, you have a weakened immune system which is your body's defense against infections, you have brain or physical disabilities, or you have 3 or more medical conditions that increase your risk such as diabetes, obesity with a body mass index of 35 or higher which is a measure of body fat based on height and weight, or long-term lung diseases
  • You must be unable or unwilling to take a medication called nirmatrelvir/ritonavir for one or more of the following reasons: you are taking medications that interact dangerously with this drug and cannot stop taking them, you are taking medications that would make this drug not work properly, you have severe liver problems, you have had bad reactions or liver damage from this drug before, the virus may be resistant to this drug, you have uncontrolled HIV infection, this drug is not approved or available in your country, or you do not want to take this drug

Who cannot join the trial?

2 criteria

  • The study does not list specific reasons why patients cannot participate, as the exclusion criteria (conditions or situations that prevent someone from joining the study) were not provided in the available information.
  • If you are interested in this study, a healthcare professional at the study site would need to review your complete medical history to determine if you meet all requirements for participation.
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Investigated drugs

Molnupiravir is an antiviral medication being tested to treat COVID-19 in adults who are not in the hospital but are at high risk of getting more seriously ill. This medicine is taken by mouth and works by helping to stop the virus from multiplying in your body. In this study, researchers want to see if this medication can help prevent people with COVID-19 from needing to go to the hospital or having other serious health problems related to the infection.

A placebo is also used in this study. A placebo looks like the real medication but does not contain any active medicine. It is used to compare against the real medication to see if the medication actually works. Some participants will receive the placebo instead of the actual medication, but neither the participants nor the doctors will know who is getting which treatment during the study.

What is already known about the treatment

Molnupiravir – Molnupiravir is an antiviral medication taken by mouth in pill form that was developed to treat COVID-19 infections in adults who are not hospitalized but have a higher risk of becoming seriously ill. This medicine works by interfering with the virus's ability to copy itself accurately, causing errors in its genetic material that prevent it from multiplying effectively in the body. It belongs to a class of drugs called antiviral agents and has been studied in clinical trials to determine if it can reduce the chances of hospitalization or death in people with COVID-19. The medication is designed to be taken early in the course of infection to help prevent the disease from getting worse.

Investigated diseases

COVID-19 – COVID-19 is an infectious disease caused by the SARS-CoV-2 virus. The disease spreads primarily through respiratory droplets when an infected person coughs, sneezes, or talks. Common signs and symptoms include fever, cough, fatigue, loss of taste or smell, and difficulty breathing. The infection can range from mild to severe, with some people experiencing no symptoms at all. In its progression, the disease typically begins with mild symptoms that may worsen over several days. Some individuals may develop complications requiring hospitalization and medical intervention.
Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2023-507227-36-00Protocol codeMK-4482-023Estimated enrolment3 082 patientsSponsorMerck Sharp & Dohme LLC

sourced from the EU Clinical Trials Register and site verification

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