Del Bigtree, a leading voice in the anti-vaccination movement, gave the nonprofit group he founded a record profit last year, according to its most recent tax filings.

The Informed Consent Action Network, known as ICAN, reported revenue of $23 million in 2023, up 74% from the previous year. The group spent nearly $17 million on efforts including litigation and anti-vaccine advocacy, an increase of about 25% from last year.

The tax documents, obtained by NBC News from ICAN, demonstrate the increasing importance and viability of the anti-vaxxer movement in the ongoing battle over vaccination policy and public health. The pandemic has provided a huge boost to groups like ICAN, which reported revenue of around $3.5 million in 2019, growing the audience interested in anti-vaccine content and the coffers of those who produce it , got bigger. Numerous studies have found that vaccines are safe and life-saving and are not linked to autism, but that hasn’t stopped the spread of misinformation.

Revenue at Children’s Health Defense, the anti-vaccine organization founded by Robert F. Kennedy Jr., had also been rising until it fell more than 30% to $16 million last year. This loss coincided with Kennedy’s departure from his positions as chairman and chief trial counsel to launch an unsuccessful presidential bid.

But ICAN’s sales continued to rise and Bigtree’s popularity increased. The former television producer and anti-vaccination filmmaker, whose organization was known for attention-grabbing stunts and filing freedom of information requests, became communications director for Kennedy’s third-party presidential campaign, advising Kennedy on preparing for his potential role as secretary of Health and Human Services.

Bigtree and ICAN did not respond to requests for comment.

Katie Miller, a spokeswoman for Kennedy’s transition team who was recently named a member of the newly created Department of Government Efficiency, said Bigtree was never involved in the transition and his views “do not reflect either the administration of Mr. Kennedy or President Trump.”

ICAN is not required to disclose individual donors, although tax documents filed last year show large donations from family foundations and donor-advised funds, philanthropic intermediaries that pool and anonymize donations.

The group has celebrated what it calls several major victories over the past year, including a lawsuit that forced Mississippi to grant religious exemptions to vaccinations. The group says it plans to pursue a similar strategy targeting the five other states that do not allow religious exemptions.

ICAN relies on individual supporters to fund the production of anti-vaccination content, including “The HighWire,” a weekly anti-vaccination and conspiracy internet show from Bigtree, which the group describes as its educational arm. Bigtree punctuates the show not with commercials but with impassioned fundraising appeals, most recently with multimillion-dollar fundraising goals related to certain legal disputes.

ICAN’s largest expenditure last year, $6 million, went to the New York law firm Siri & Glimstad, which pursues public records requests, intervenes in state anti-vaccine battles and petitions the federal government to suspend it or requested cancellation of vaccinations, including one against polio. Led by Aaron Siri, a lawyer and Kennedy adviser, the firm, supported by dozens of lawyers working on vaccine cases, has paid ICAN about $20 million since 2017, according to tax filings.

Siri defended his work in an email to NBC News, saying his petitions were aimed at increasing vaccine safety and that ICAN’s financial support was “trivial” compared to the pharmaceutical industry’s spending.

Miller said Siri is no longer involved in the transition and he does not represent Kennedy’s views.

ICAN describes its legal efforts as “advocating for humanity’s right to informed consent.” Experts have described it as exploitation of the courts. “This anti-vaccination group has consistently misrepresented both the legal and factual meaning of court decisions, settlements and other legal actions to create a narrative that galvanizes its followers and influences newcomers,” says a 2022 article in the Read Northwestern Journal of Law and Social Policy. (Siri called the article “full of categorically false claims.”)

The intent of other editions was less clear. ICAN paid $176,000 for “research advice” to a British company led by a chiropractor who gave a talk about the dangers he said posed by vaccines and 5G technology. The group also paid $152,000 for consulting for Uncover DC, a news website founded and edited by Tracy Diaz, known online as Tracy Beanz, a popular conspiracy theorist and early promoter of the QAnon movement. Diaz, who describes her website as “real journalism,” publishes press releases for ICAN and is a contributor to the nonprofit’s website.

Bigtree took home a salary of $234,000 from ICAN in 2023, in addition to his income from paid speaking engagements (he says he only charges for ticketed events). Bigtree also earned $350,000 for consulting and communications work on Kennedy’s presidential campaign over the past two years through KFP Consulting, a Texas organization registered with Bigtree.

Bigtree now runs a super PAC (MAHA Alliance) and a nonprofit (MAHA Action), both short for “Make America Healthy Again,” a variation of Trump’s MAGA motto that Kennedy adopted after he dropped out of the race and supported the ultimately winning candidate.

Bigtree acknowledged his diverse sources of income and efforts on The HighWire in November. “I feel incredibly blessed by God to have had all these opportunities at once,” he said.