Regeneron

Eli Lilly's monoclonal antibody will be available to people 65 or older or those with underlying health conditions. Supplies will be short, and allocating the medicine will be a challenge.

The federal government plans to distribute 300,000 doses of the drug at no cost, but that doesn't mean treatment will be free. Intravenous infusion charges can run more than $1,000.

President Trump is "doing very well," his physician told reporters on Saturday morning, but a source familiar with the president's health later told White House pool reporters, that "the president's vitals over the last 24 hours were very concerning."