President Trump named Vice President Mike Pence his point person to coordinate the government’s response to the coronavirus, expressing confidence that the United States would prevent a widespread domestic outbreak. Mr. Trump’s announcement, at a White House news conference, came after two days of contradictory messages from government officials about the dangers posed to Americans by the virus, which first emerged in China and has infected more than 81,000 people globally, killing nearly 3,000. He also expressed confidence that scientists would develop a vaccine, but he provided no details.

“We’re very, very ready for this,” he said.