WASHINGTON — The White House moved on Thursday to tighten control of coronavirus messaging by government health officials and scientists, directing them to coordinate all statements and public appearances with the office of Vice President Mike Pence, according to several officials familiar with the new approach.

But on a day that the White House sought to display a more disciplined strategy to the administration’s communications about the virus, Mr. Trump used an evening event honoring African-American History Month to rail against the news media, claiming it is overstating the threat, and to congratulate himself for keeping the number of cases low.

“I think it’s an incredible achievement what our country’s done,” Mr. Trump said, noting that he had moved quickly to ban travel from China after the emergence of the virus. Even though a total of 60 people infected with the coronavirus are in the United States, he ignored all but the 15 who did not initially contract it overseas.

“Fifteen people is almost, I would say, a miracle,” the president bragged.

The comments came just a few hours after Mr. Pence convened a meeting of the coronavirus task force composed of some of the nation’s top public health officials. The vice president made it clear that they would report to him.