Health Secretary Robert F. Kennedy Jr., who has long questioned the safety of vaccines, is planning a broad federal effort to address vaccine injuries, including a new research clinic at the National Institutes of Health and a new billing code to reimburse doctors for filing reports of serious vaccine side effects, according to multiple people familiar with the initiative.

Mr. Kennedy talked about the initiative when he and other top health officials made an unannounced visit to the N.I.H. in Bethesda, Md., earlier this week — his first trip there as secretary — to meet with patients who believe they have been injured by vaccines, according to the people, who insisted on anonymity because they were not authorized to discuss it.

Officials at the Department of Health and Human Services did not respond to requests for comment about the initiative. A spokesman for Dr. Jay Bhattacharya, the N.I.H. director, declined comment. Some details of the initiative were earlier reported by Bloomberg.

Mr. Kennedy’s efforts to focus government resources on vaccine injuries comes as vaccine-preventable diseases, including measles, are rising in the United States because of falling vaccination rates.

Like all drugs, vaccines cause side effects, but public health experts say the benefits far outweigh the risks for most people. The World Health Organization estimated in 2024 that global immunization efforts have saved 154 million lives over the past half-century. Vaccines have wiped out smallpox and mostly relegated polio to the history books.

Although injuries are rare, vaccine experts generally support close monitoring and continued study of side effects. Many are wary of Mr. Kennedy’s motivations, however, and they say that until more details of the initiative are known, it is impossible to say whether or not it will be a legitimate exercise in science.