An unsubstantiated claim two weeks ago by President Donald Trump — that the “deep state” was slowing approval of a Covid-19 vaccine — has set off an effort by government officials and private industry to ensure the White House doesn’t interfere with a methodical, careful scientific process.

Leaders of the U.S. Food and Drug Administration leaders are trying to insulate the agency’s vaccine reviewers from outside political pressure, and drug companies have vowed to make a safe vaccine. Drew Armstrong reports on how government agencies and companies are doing to reassure the public a vaccine will be safe.