U.S. health regulators are expected to make public on Friday a staff review about the promising Covid-19 pill from Merck & Co. and Ridgeback Biotherapeutics LP.

The report from Food and Drug Administration staff is expected to include an analysis of clinical-trial data for the drug, molnupiravir, which the companies say reduces the risk of hospitalization and dying in people at high risk of severe Covid-19 infections.

The...

U.S. health regulators are expected to make public on Friday a staff review about the promising Covid-19 pill from Merck & Co. and Ridgeback Biotherapeutics LP.

The report from Food and Drug Administration staff is expected to include an analysis of clinical-trial data for the drug, molnupiravir, which the companies say reduces the risk of hospitalization and dying in people at high risk of severe Covid-19 infections.

The report may also provide the staff’s opinion about whether the agency should clear the drug for use.

Molnupiravir, and another experimental antiviral from Pfizer Inc. that is also under FDA review, promise to fill a big gap in Covid-19 treatment for a pill that people could easily take at home to keep them out of the hospital.

So far, people at high risk of severe disease seeking to avoid hospitalization have had to go to a hospital or clinic that can inject or infuse an antibody drug.

The U.K. cleared molnupiravir for use earlier this month.

FDA staff reviews are a routine part of the regulatory evaluation process before the agency decides whether to green light a product. Merck and Ridgeback requested emergency use authorization last month.

The FDA is also due to make public a report about molnupiravir from the companies.

The reports will be discussed Tuesday when an outside panel of advisers to the FDA meets and votes whether to recommend the agency clear the drug for use.

The FDA isn’t required to follow the panel’s advice but normally does. Should the panel give a thumbs-up, an FDA decision could come before the end of the year.

SHARE YOUR THOUGHTS

How would a Covid-19 pill help in the battle against the pandemic? Join the conversation below.

The agency hasn’t scheduled a meeting of the panel to review Pfizer’s drug, called Paxlovid.

Researchers designed molnupiravir to work by mucking up the virus’s ability to replicate, by introducing errors into its genetic code. A course of treatment is eight pills daily for five days, started within five days of showing symptoms.

In a key study, researchers found molnupiravir cut in half the risk of hospitalization or death in high-risk people with mild to moderate Covid-19.

Some scientists have expressed concern about the safety of the drug and whether it might cause mutations in cells that are harmful to people.

Doctors are increasingly turning to monoclonal-antibody drugs to treat high-risk patients who get sick with Covid-19. WSJ takes a look at how the therapies work and why they’re important for saving lives. Illustration: Jacob Reynolds/WSJ The Wall Street Journal Interactive Edition

Mutations were seen when researchers exposed Chinese hamster ovary cells in a lab to the drug compound for 32 days, but Merck says its testing has found the drug safe for people. Merck said diarrhea and nausea were the most common side effects in trial subjects who took molnupiravir.

The company plans to manufacture 10 million courses of treatment by the end of the year and at least double that amount next year.

Merck has agreed to provide the U.S. government 3.1 million courses of molnupiravir for about $2.2 billion, should regulators clear the pill for use.

The Biden administration is expected to allocate the supply to states, which in turn will direct them to pharmacies, hospitals and doctor’s offices.

The administration is also exploring avenues to expand access to the pills from Merck and Pfizer, should they be cleared for use. Among the options are making them available in the commercial market, even if authorized for emergency use, and allowing Medicare and Medicaid coverage, The Wall Street Journal has reported.

Write to Jared S. Hopkins at jared.hopkins@wsj.com and Betsy McKay at betsy.mckay+1@wsj.com