Children’s Health Defense, the anti-vaccine nonprofit group founded by Robert F. Kennedy Jr., recorded a more than 30% drop in revenue last year, according to recent tax filings.

The top US public health official warned about the threat of curtailing vaccination efforts as longtime skeptic Robert F. Kennedy Jr. prepares for an influential role in the incoming Trump administration.

Robert F. Kennedy has been critical of immunizations, contending they lack effectiveness and have links to autism, claims that have been debunked.

With President-elect Donald Trump in the White House, the 21st century may be another story. Robert F. Kennedy Jr., whom Trump has pledged to let “go wild” on public health under his administration, is an outspoken opponent of adding fluoride to drinking water. He intends to take action.

Kennedy Jr. has previously said that if Republican President-elect Donald Trump won the White House, the administration would advise water systems in the United States to remove fluoride. This is despite experts and officials saying the mineral is both safe and beneficial to people’s dental health.