In a 2015 speech, Bill Gates warned that the greatest risk to humanity was not nuclear war but an infectious virus that could threaten the lives of millions of people.

That speech has resurfaced in recent weeks with 25 million new views on YouTube — but not in the way that Mr. Gates probably intended. Anti-vaccinators, members of the conspiracy group QAnon and right-wing pundits have instead seized on the video as evidence that one of the world’s richest men planned to use a pandemic to wrest control of the global health system.

Mr. Gates, 64, the Microsoft co-founder turned philanthropist, has now become the star of an explosion of conspiracy theories about the coronavirus outbreak. In posts on YouTube, Facebook and Twitter, he is being falsely portrayed as the creator of Covid-19, as a profiteer from a virus vaccine, and as part of a dastardly plot to use the illness to cull or surveil the global population.

The wild claims have gained traction with conservative pundits like Laura Ingraham and anti-vaccinators such as Robert F. Kennedy Jr. as Mr. Gates has emerged as a vocal counterweight to President Trump on the coronavirus. For weeks, Mr. Gates has appeared on TV, on op-ed pages and in Reddit forums calling for stay-at-home policies, expanded testing and vaccine development. And without naming Mr. Trump, he has criticized the president’s policies, including this week’s move to cut funding to the World Health Organization.

Misinformation about Mr. Gates is now the most widespread of all coronavirus falsehoods tracked by Zignal Labs, a media analysis company. The misinformation includes more than 16,000 posts on Facebook this year about Mr. Gates and the virus that were liked and commented on nearly 900,000 times, according to a New York Times analysis. On YouTube, the 10 most popular videos spreading lies about Mr. Gates posted in March and April were viewed almost five million times.

Mr. Gates, who is worth more than $100 billion, has effectively assumed the role occupied by George Soros, the billionaire financier and Democratic donor who has been a villain for the right. That makes Mr. Gates the latest individual — along with Dr. Anthony Fauci, the leading U.S. infectious disease expert — to be ensnared in the flow of right-wing punditry that has denigrated those who appear at odds with Mr. Trump on the virus.

“Bill Gates is easily transformed into a health-related meme and figure because he’s so well known,” said Whitney Phillips, an assistant professor at Syracuse University who teaches digital ethics. “He’s able to function as kind of an abstract boogeyman.”

Especially since Mr. Gates has sharpened his comments about the White House’s handling of the coronavirus in recent weeks.

“There’s no question the United States missed the opportunity to get ahead of the novel coronavirus,” he wrote in an opinion column in The Washington Post on March 31. “The choices we and our leaders make now will have an enormous impact on how soon case numbers start to go down, how long the economy remains shut down and how many Americans will have to bury a loved one because of Covid-19.”

Mark Suzman, chief executive of the Bill & Melinda Gates Foundation, Mr. Gates’s main philanthropic vehicle, said it was “distressing that there are people spreading misinformation when we should all be looking for ways to collaborate and save lives.”

Through a representative, Mr. Gates declined to interviewed.

The conspiracy theories about Mr. Gates may particularly damage what people think about a future coronavirus vaccine, said Claire Wardle, executive director of First Draft, an organization that fights online disinformation. She said the narratives “have the potential to kick off coordinated and sophisticated online campaigns that turn people against taking a virus vaccine.”

YouTube, Twitter and Facebook, which also owns Instagram, said they were fighting coronavirus misinformation.

Mr. Gates, who founded Microsoft with Paul Allen in 1975 and built it into a software behemoth, has largely devoted his time to philanthropic endeavors since he stepped back from the company in 2008. As of 2018, the Gates Foundation had a $46.8 billion endowment, making it one of the world’s largest private charitable organizations.

The foundation has worked to distribute vaccines in developing countries, advocated family planning through greater use of contraceptives and funded the development of genetically modified crops. Those efforts have prompted unfounded accusations that Mr. Gates was hurting the world’s poor with unnecessary drugs and harmful crops while trying to suppress the global population.

His disdain for Mr. Trump, whom he has met several times, has also become public. In 2018, footage surfaced of Mr. Gates recounting how Mr. Trump needed help distinguishing H.I.V., which refers to the human immunodeficiency virus and causes AIDS, from HPV, which is the human papillomavirus, a sexually transmitted infection.

“Both times he wanted to know if there was a difference between H.I.V. and HPV, so I was able to explain that those are rarely confused with each other,” Mr. Gates said to laughter in comments to his foundation.

In January, when the coronavirus began spreading, the Gates Foundation committed $10 million to helping medical workers in China and Africa. In February, Mr. Gates weighed in on the illness, warning in The New England Journal of Medicine that Covid-19 was behaving like a once-a-century pathogen.

In addition to writing the Washington Post op-ed, he called for more and equitable testing in a Reddit “Ask Me Anything” session last month. This month, Mr. Gates appeared on “The Daily Show” and said his foundation would fund factories for the seven most promising potential vaccines.

On Wednesday, the Gates Foundation said it would commit $250 million — up from an earlier pledge of $100 million — to slow the disease’s spread.

By then, falsehoods about Mr. Gates had taken off. The first mention of a baseless conspiracy connecting him to the outbreak was on Jan. 21, according to the Times analysis. That was when a YouTube personality linked to QAnon suggested on Twitter that Mr. Gates had foreknowledge of the pandemic. The tweet was based on a coronavirus-related patent from the Pirbright Institute, a British group that received funding from the Gates Foundation.

The patent was not for Covid-19; it was connected to a potential vaccine for a different coronavirus that affects poultry. But two days later, the conspiracy website Infowars inaccurately said the patent was for “the deadly virus.”

The idea spread. From February to April, conspiracy theories involving Mr. Gates and the virus were mentioned 1.2 million times on social media and television broadcasts, according to Zignal Labs. That was 33 percent more often, it said, than the next-largest conspiracy theory: that 5G radio waves cause people to succumb to Covid-19.

Some of the theories tapped into Mr. Gates’s acquaintance with Jeffrey Epstein, the financier who was convicted of sex trafficking and committed suicide, saying a global elite had banded together to create the coronavirus.

In other theories, internet trolls twisted comments that Mr. Gates had made. In one, trolls said Mr. Gates, who had raised the idea of “digital certificates” to confirm who had the virus, wanted to surveil the population with microchip vaccination implants.

By April, false Gates conspiracy theories peaked at 18,000 mentions a day, Zignal Labs said.

The theories were amplified by people such as Mr. Kennedy, a son of former Senator Robert F. Kennedy, who campaigns against vaccines as a director of the Children’s Health Defense network. On his Instagram page, Mr. Kennedy has said Mr. Gates pushes vaccines to feed his other business interests.

On Tuesday, Mr. Kennedy posted a cartoon of a smiling Mr. Gates with a syringe and a caption: “Your Body, my choice.”

Mr. Kennedy, whose Instagram followers have doubled to more than 285,000 since March, said in an interview that he was telling the truth about the “terrible damage” that Mr. Gates had inflicted on the world with vaccines.

In an April 7 tweet, Ms. Ingraham, a Fox News host, shared a conspiracy theory about nefarious motives behind Mr. Gates’s call to track and identify who had received a Covid-19 vaccine. “Digitally tracking Americans’ every move has been a dream of the globalists for years,” she wrote.

Ms. Ingraham did not respond to a request for comment.

And Roger J. Stone Jr., the Trump confidant who was sentenced this year to 40 months in prison for felonies related to the 2016 Trump campaign, said in a radio interview this week reported by The New York Post that whether Mr. Gates “played some role in the creation and spread of this virus is open for vigorous debate.”

On Wednesday, after Mr. Gates said pulling funding to the World Health Organization was ill advised, the online reaction was swift. (The Gates Foundation funds the organization.)

One anti-vaccinator posted a poster of the movie “Kill Bill” on Instagram that read “Kill Bill Gates” and called for people to flood the comments on Mr. Gates’s Instagram account.

That same day, when Mr. Gates posted his thanks to health care workers, it received over 14,000 comments. One read: “This virus is a big, big lie.”

Michael H. Keller contributed reporting. Ben Decker contributed research.

The post Bill Gates, at Odds With Trump on Virus, Becomes a Right-Wing Target appeared first on New York Times.