NORTH CHARLESTON, S.C. — Larry Kudlow, the president’s chief economic adviser, stood in the White House briefing room on Friday urging the public — and the plunging financial markets — not to panic over the coronavirus outbreak, while Vice President Mike Pence spread a similar message to officials and residents at an event in Florida.

Later, as the authorities revealed a second person in California had been found to be infected with the coronavirus without having any known risk factors, President Trump suggested the panic over the issue was being manufactured by his enemies.

In South Carolina on Friday night at his latest freestyle “Keep America Great” rally, the president accused Democrats of treating alarm over the coronavirus as “their new hoax,” and said the news media was in “hysteria mode” over his administration’s handling of the outbreak, continuing an attempt to shift blame for a public health crisis onto his political adversaries.

“Now the Democrats are politicizing the coronavirus,” Mr. Trump told a crowd of supporters, who roared in response. “They can’t even count their votes in Iowa.”