For the past ten years, Dr. Mercola built a huge company to promote natural health regimens, spread and benefit from anti-vaccination content, said researchers who studied its network. In 2017, he filed an affidavit claiming his net worth was “over $ 100 million”.

And instead of saying directly online that vaccines aren’t working, Dr. Mercola’s posts often ask specific questions about her safety and discuss studies that other doctors have refuted. Facebook and Twitter have allowed some of its posts to be kept cautious, and companies have struggled to establish rules to remove nuanced posts.

“He was breathed new life through social media, which he cleverly and ruthlessly exploited to captivate people,” said Imran Ahmed, director of the Center for Countering Digital Hate, which investigates misinformation and hate speech. His “Disinformation Dozen” report has been quoted in Congressional hearings and by the White House.

In an email, Dr. Mercola, it is “quite strange for me that I am being referred to as number 1 in disseminating misinformation”. Some of his Facebook posts were only liked by hundreds of people, he said, so he didn’t understand “how the relatively small number of shares in Biden’s multi-billion dollar vaccination campaign could so devastate”.

The efforts against him are political, added Dr. Mercola added, accusing the White House of “illegal censorship through collusion with social media companies.”

He did not elaborate on whether his claims about the coronavirus were real. “I am the lead author of a peer-reviewed publication on vitamin D and the risk of Covid-19 and I have the right to inform the public by sharing my medical research,” he said. He failed to identify the publication, and The Times was unable to verify his claim.

Updated

July 24, 2021, 10:55 a.m. ET

Dr. Mercola is from Chicago and started a small private practice 1985 in Schaumburg, Illinois. He switched to naturopathy in the 1990s and opened his main website Mercola.com to share his treatments, cures and advice. The website urges people to “take control of your health”.