The drugmaker announced Wednesday it will distribute the coronavirus vaccine for the first time in the United States.
The vaccine will be given to people who live in regions where the virus is present in large numbers, according to Merck.
The U.S. Department of Health and Human Services has said that about 80 percent of people living in counties where the coronvirus has been detected will receive the vaccine, and it will be distributed through the Food and Drug Administration.
But there are some safety concerns, including the possibility that people who have received the vaccine may have weakened immune systems.
The coronaviruses cause a variety of serious conditions and are deadly to humans.
Merck has said it will release a full-dose vaccine, but it has not yet announced a time frame for when it will begin to distribute it.
Merck shares rose nearly 4 percent Wednesday, to $77.30.