This study tests a medicine called Molnupiravir (also known as MK-4482) to see if it can help prevent people from getting very sick from COVID-19. COVID-19 is a virus that can cause mild symptoms like a cold or flu, but some people with certain health problems are at higher risk of getting really sick. Molnupiravir works by stopping the virus from multiplying in the body. The study compares Molnupiravir to a placebo, which is a pill with no medicine, to see if it works better.

• The study is for people aged 18 and older who have tested positive for COVID-19 in the last 4 days and have symptoms.
• Participants should have at least one high-risk condition, like being over 75 years old or having a serious health issue.
• People can't join if they are already hospitalized for COVID-19 or have received certain COVID-19 treatments recently.

This study does not allow people who are already in the hospital or have had a COVID-19 vaccine in the last 30 days. Participants might receive standard care with another medicine called remdesivir if needed. Joining this study might help researchers find better ways to treat COVID-19 in high-risk people.