Kolina Koltai first heard about the coronavirus back in January, but not from newspapers or TV. Instead, she read about it in anti-vaccination groups on Facebook.
"They were posting stories from China like, 'Hey, here's this mysterious illness,' or 'Here's this something that seems to be spreading,'" she said.
While few others in the U.S. were talking about the virus back then, people opposed to vaccination were paying attention, Koltai said, because they have long worried that a new disease would trigger the creation of a vaccine that, in their view, could be "forced onto everyone."
Koltai is well versed in these kinds of conspiracy theories about vaccines. A researcher at the University of Washington's Center for an Informed Public, she has studied the growing anti-vaccination movement on Facebook since 2015.
Until recently, such claims circulated mostly in groups dedicated to vaccine scrutiny, alternative health and parenting. But the pandemic has created what she called "the perfect storm" for vaccine misinformation to hit the mainstream.
"There's so much we don't know, so much uncertainty and uncertainty makes us all so prone to misinformation to try to quell that feeling," she said.
Falsehoods have multiplied and can be found anywhere from neighborhood chats to groups for pet owners, because so many people have questions about the COVID-19 vaccines. The hoaxes also have been propelled by groups opposed to lockdowns and mask wearing, and by proponents of Qanon, a fact-defying, pro-Trump conspiracy theory.
The discredited claims in a video titled "Plandemic" that went viral this summer, thanks in part to conspiracy theorists, echoed falsehoods Koltai had seen earlier in the Facebook groups she follows.
"The summary was essentially that this was all part of a larger plan — to use the word 'plandemic' — to either mess with President Trump or as a way to force vaccines," she said. "Part of a larger narrative that they're going to force things onto us to get to this new world order."
Baseless claims that the virus was planned and that vaccines will be used to track or control people rank among the most mentioned pieces of misinformation this year, according to Zignal Labs, a media analytics company.
The spread of false claims about the vaccines on social media is so troubling because it risks undermining public health efforts. Dr. Anthony Fauci, head of the National Institute of Allergy and Infectious Diseases, said last week that 75 to 85 percent of people need to get vaccinated to bring the pandemic to heel, let the economy recover and enable people to get back to their daily routines.
A recent Gallup survey found 37 percent of Americans are not willing to get a COVID vaccine, versus 63 percent who are.
Imran Ahmed, CEO of the nonprofit Center for Countering Digital Hate, which tracks online misinformation, calls the spread of vaccine misinformation "a really powerful parallel pandemic to the real pandemic."
A YouGov survey his group commissioned this summer found people in the U.S. and U.K. who rely on social media for information about the pandemic were less likely to say they would get a COVID vaccine than those who get their news from traditional media.
The group also found the 150 largest anti-vaccination accounts on social media gained 8 million followers since January.
Ahmed says these twin pandemics amplify each other. "One being biological and one being social, [they] are working in concert to really undermine our capacity to contain COVID," he said.
The social networks are well aware of the problem. Facebook, Google's YouTube and TikTok say they are removing debunked claims about COVID vaccines. Twitter says it's still working on its policy.
Recently, Facebook took down some of the biggest anti-vaccination groups and pages.
Ahmed says, even with these moves, public health officials face an uphill battle to persuade enough people to get vaccinated, while vaccine opponents have a lower bar.
"Their job is not to persuade people not to take a vaccine, it's to inject doubt," he said. "That's it. That's all you've got to do for their side."
Editor's note: Facebook, Google and TikTok are among NPR's financial supporters.