The US Department of Health and Human Services launched a program this week to investigate and document the scope of vaccine injuries, reviving a longtime priority for HHS Secretary Robert F. Kennedy Jr. while drawing concern from some public health advocates.

Kennedy unveiled the vaccine injury research center Monday during a visit to the US National Institutes of Health. The program will be based at the federal research agency.

“Vaccine injury is an invisible disease, and it is purposely invisible,” Kennedy said during the event, according to footage shared by HHS. “We have not done the studies that need to be done to understand who’s vulnerable to those kind of injuries.”

The initiative arrives alongside several proposals to change the federal system used to report adverse events. HHS also wants to reimburse doctors who report suspected vaccine injuries, which the department said will “encourage” health care workers to submit reports.

The US Centers for Disease Control and Prevention says on its website that vaccines carry a “very remote chance” of causing serious reactions, injuries or death. Kennedy, however, has claimed that federal scientists ignored possible side effects.

Those claims have included debunked theories linking immunizations to autism and have energized Kennedy’s Make America Healthy Again base. The new research effort places his arguments about vaccine safety at the center of a federal health initiative.

Kennedy previewed the proposed changes last month while speaking to Children’s Health Defense, the group opposed to vaccines that he cofounded and helped lead. He stepped away from the organization before running for the presidency.

During that speech, Kennedy called the federal Vaccine Adverse Event Reporting System “very bad.” He said vaccine injuries could be “very rare,” but argued that their frequency is unknown under the current reporting system.

“In our country, we care about rare illnesses and deaths. We care about every child who dies from measles. They get headlines. We should care about the children — shouldn’t we, I’d ask you, care about children who are dying or suffering or being injured by vaccine injuries?” Kennedy told the crowd on September 17.

Dr. Peter Hotez, codirector of the Texas Children’s Hospital Center for Vaccine Development, told CNN that the existing US monitoring system already performs well. Hotez is also dean of the National School of Tropical Medicine at the Baylor College of Medicine.

“The US already has the most advanced sophisticated system of vaccine monitoring the world has ever seen, with multiple redundant systems in place,” Hotez said. He pointed to the system’s detection of extremely rare side effects associated with COVID vaccinations during the pandemic.

Those findings included myocarditis among young men who received mRNA vaccines, occurring at a rate of about 1 in 20,000. The system also identified blood clots associated with the Johnson & Johnson vaccine at a rate of about 1 in 500,000.

Hotez said he views the HHS actions as an attempt to sow doubt about vaccines while vaccination rates are declining and illnesses preventable through vaccines are returning. Pennsylvania is currently experiencing the nation’s worst measles outbreak in decades.

HHS officials have publicly disputed state authorities over the number of people who have died from measles this year. Pennsylvania has reported five deaths related to measles, all among unvaccinated people, as the statewide case count has risen above 1,000.

Kennedy presented the vaccine injury actions as another attempt to restore public trust in health care institutions. KFF polling from February, however, found that Americans’ trust in the CDC had declined amid agency changes led by Kennedy.

Pew Research Center polling conducted last fall found that most voters across political parties felt confident in the childhood vaccine schedule. That survey occurred before Kennedy introduced a narrowed immunization schedule in December and presented the plan again this summer.

Dr. Paul Offit, director of the Vaccine Education Center at the Children’s Hospital of Pennsylvania, said the initiative gives Kennedy a platform for beliefs not proved by science. “Now he’s in a position to be able to create the kinds of studies that fit that bias,” Offit said.