During the early days of the coronavirus pandemic in the spring of 2020, President Trump was warned by medical officials that the development of a vaccine that could turn the tide against Covid could be over a year away.
For Mr. Trump, that timeline was not good enough.
He demanded a faster program. The creation of that program, Operation Warp Speed, led to lifesaving vaccines that contained messenger RNA, or mRNA, a synthetic form of a genetic molecule that helps stimulate the immune system. Those vaccines are widely regarded in the scientific community as the quickest way to protect Americans against future threats, including viruses that could mushroom into a pandemic, or man-made menaces, like a bioweapons attack.
Time has marched on and, apparently, so has Mr. Trump in his second term.
This week, the president all but shrugged off an announcement by Robert F. Kennedy Jr., the health and human services secretary and a longtime critic of vaccines, that a research division of his department had slashed $500 million in grants and contracts for work on mRNA vaccines.
“That was now a long time ago, and we’re onto other things,” the president told reporters on Wednesday. Mr. Trump added that his administration is now “looking for other answers to other problems, to other sicknesses and diseases.” He said he was planning to meet with Mr. Kennedy on Thursday to discuss the decision, but by Friday, White House officials did not say whether that meeting took place.
Mr. Trump’s willingness to give Mr. Kennedy the space to impose his views is notable, given that the vaccines were once seen as legacy achievement during Mr. Trump’s first term. But his laissez-faire posture also leaves room for Mr. Trump to position himself in line with the portion of his base that has grown deeply skeptical about the safety and efficacy of vaccines.
In recent months, Mr. Trump has offered little to no public input as Mr. Kennedy fired a 17-member committee at the Centers for Disease Control and Prevention that makes vaccine recommendations; appointed advisers who have rescinded some flu vaccine recommendations; and suggested, contrary to evidence, that many pediatricians make money from vaccines.
Mr. Trump has also said there is nobody better than Mr. Kennedy to explore the debunked theory that vaccines cause autism. Mr. Kennedy is expected to release a report airing those findings in September.
Mr. Kennedy, a former presidential challenger to Mr. Trump, abandoned his campaign last summer and pledged his support to Mr. Trump. But he remains the champion of an influential “medical freedom” movement that promotes nontraditional medicines or supplements and eschews many regulatory health practices that have long been embraced by the scientific community.
Adm. Brett Giroir, an assistant health secretary in the first Trump administration who was involved in the development of the Covid vaccines, recalled that the president had been “very pro-vaccine,” particularly on matters involving flu preparedness. In 2019, Mr. Trump signed an executive order calling for the modernization of flu vaccines, because “he knew we weren’t as well prepared as we should be.”
Admiral Giroir said Mr. Trump encouraged debate during meetings over a range of topics, but ultimately had embraced a broad array of public health efforts. Mr. Trump declared Americans’ reliance on opioids a public health emergency. At his State of the Union address in 2019, Mr. Trump outlined an initiative to end H.I.V. Amid political blowback, he approved a limited ban on flavored e-cigarette cartridges.
The crew of advisers and experts who counseled Mr. Trump on health initiatives during his first term have either moved on or been targeted by the same forces that aided Mr. Kennedy’s rise. Several of those initiatives have been scaled back, including efforts surrounding H.I.V. prevention and curbing smoking.
Mr. Kennedy’s latest claims about mRNA vaccines, including that they were not effective against respiratory diseases, were “patently false,” Admiral Giroir said. He added that they were at odds with “the policy of the President Trump I knew.”
A White House official, who was not authorized to speak publicly, said on Friday that the administration was not against vaccines but that the president and his advisers want to find other vaccines that could be more effective. This week, Mr. Kennedy told reporters that the administration is putting funding toward developing a universal vaccine that could be more effective in addressing public health emergencies.
Critics believe the administration’s other pursuits should not come at the expense of working on vaccines that saved millions of lives. Senator Bill Cassidy, Republican of Louisiana, said the decision to take away the funding threatened to undermine Mr. Trump’s agenda.
“It is unfortunate that the Secretary just canceled a half a billion worth of work, wasting the money which is already invested,” Mr. Cassidy, a physician who voted to confirm Mr. Kennedy, wrote on social media on Wednesday. “He has also conceded to China an important technology needed to combat cancer and infectious disease.”
He added: “President Trump wants to Make America Healthy Again and Make America Great Again. This works against both of President Trump’s goals.”
According to a release from the Department of Health and Human Services, some contracts in their final stages would be completed, but no new projects would be started.