The idea that he is the inventor of mRNA vaccines is “a totally false claim,” said Dr. Gyula Acsadi, a pediatrician in Connecticut who along with Dr. Malone and five others wrote a widely cited paper in 1990 showing that injecting RNA into muscle could produce proteins. (The Pfizer and Moderna vaccines work by injecting RNA into arm muscles that produce copies of the “spike protein” found on the outside of the coronavirus. The human immune system identifies that protein, attacks it and then remembers how to defeat it.)

But Dr. Malone was not the lead author on the paper and, according to Dr. Acsadi, did not make a significant contribution to the research. While the paper stated that the technology could “provide alternative approaches to vaccine development,” Dr. Acsadi said none of the other authors would claim that they invented the vaccine.

“Some of his work was important,” said Dr. Alastair McAlpine, a pediatric infectious disease doctor based in Vancouver, British Columbia, “but that’s a long way away from claiming to have invented the technology that underpins the vaccines as we use them today.”

The vaccines “are the result of hundreds of scientists all over the world, all combining to come together to form this vaccine,” Dr. McAlpine said. “It was not one individual or the pioneering work of an individual person.”

A spokeswoman for Penn Medicine said, “We have been excited to witness the deployment of the vaccines in the global fight against the virus and the well-deserved global recognition for Drs. Kariko and Weissman’s decades of visionary basic science research.”

Dr. Malone pushes back against the criticism directed at him by scientists, researchers and journalists, and dismisses the dozens of fact-checks disputing his statements as “attacks.”

He also continues to repeat his claims, with the help of his wife, Dr. Glasspool Malone, who is trained in biotechnology and public policy. She writes, he said, more than half of the articles posted onto his Substack newsletter — which is awash in conspiracy theories about the Covid-19 vaccines. Recent articles include “The illusion of evidence-based medicine” and “How does it feel to be vindicated?”

Dr. Malone said he did not align himself with any particular political party. But in recent months, he and his wife have made numerous stops at popular conservative conferences, like Hereticon, the Peter Thiel-backed conference in Miami for Silicon Valley’s self-proclaimed contrarians, and the “Defeat the Mandates” march in Washington.

Dr. Malone says much of the pushback he receives is because anything that questions the guidance from organizations like the World Health Organization and the Centers for Disease Control and Prevention is automatically labeled misinformation by the medical establishment, as well as the technology platforms.

Many well-meaning public figures and donors committed themselves to the wrong ideas, just to be able to tell themselves that they are indeed playing a role helping to solve the crisis, he said.

“It is really easy to get caught up in it, and obsess, and lose perspective — and kind of lose yourself,” Dr. Malone said of them.

Many scientists and researchers say there is good-faith disagreement about how to translate fast-moving science into policy, and acknowledge that health agencies have adjusted guidelines over time, as new information is collected.

Dr. Angela Rasmussen, a virologist at the Vaccine and Infectious Disease Organization at the University of Saskatchewan, said such guidance was “only as reliable as the evidence behind it, and thus it should change when new evidence is obtained.”

But they say Dr. Malone has twisted legitimate policy debates to use them as cover for continuing to spread misinformation and to advance claims about the pandemic that are demonstrably incorrect.

Months ago, he was promoting the drugs hydroxychloroquine and ivermectin for treatment of Covid-19, despite several studies and scientific trials showing a lack of evidence that the drugs improved the conditions of Covid patients. Dr. Malone said that early on in the pandemic, he believed that what he could contribute was bringing repurposed drugs to market.

“All the big boys came in for the vaccines,” Dr. Malone said. “We weren’t needed for that.”

The Food and Drug Administration continues to caution against the use of hydroxychloroquine “due to risk of heart rhythm problems,” and a large study published in March found that ivermectin does not reduce the risk of Covid hospitalization. The F.D.A. has also said taking large doses of the drug is dangerous.

“Robert Malone is exploiting the fact that data-driven course correction is inherent to the scientific process to peddle disinformation,” Dr. Rasmussen said. “It’s extraordinarily dishonest and morally bankrupt.”