Even some state lawmakers used the news to imply vaccines aren't safe. One Pennsylvania state legislator, Rep. Rob Kauffman, posted to his 13,700 Facebook followers that "we don't fully understand these vaccines."

A trending topic means opportunity

In most cases, the social media companies say they can't do much to respond in cases such as this, since people largely are sharing articles based on factual information, even if the commentary and subtext around the posting is meant to further false ideas.

"It's a really insidious problem," said Deen Freelon, a communications professor at the University of North Carolina at Chapel Hill, in an interview with NPR last month. "The social media companies have taken a hard line against disinformation; they have not taken a similarly hard line against fallacies."

Many anti-vaccine activists have adopted this tactic as a way of getting around social media networks' policies designed to halt the spread of false information.

An0maly, the influencer with the widely shared posting about the Johnson & Johnson vaccine, shared a CNN story with a misleading caption to his 1.5 million Facebook followers.

"The issue is this is a factual report," said Sarah Roberts, an information studies professor at UCLA. "But the people reading the report either have such deeply held preconceived notions about its meaning or they lack appropriate context to receive the information."

Overall, it's hard to overstate the degree to which the Johnson & Johnson story blew up online.

The company was getting as many mentions online every hour Tuesday as it had during entire weeks before the news, according to data from Zignal.

Much of those mentions were not in reference to misinformation, but Zignal's Granston said anytime interest in a topic spikes like that online, especially with a polarizing subject such as vaccines, it provides a ripe environment for misinformation as well.

"These big conversations provide this huge platform for people to further a specific agenda around this information," she said.

Zignal saw an uptick in mentions of narratives about side effects but also in other vaccine misinformation narratives unrelated to the actual news such as vaccine passports, deaths and microchips.

Disinformation economy

The Johnson & Johnson pause is also fertile ground for conspiracies because it is a developing topic with a number of unanswered questions.

Often, misinformation peddlers with a specific agenda will fill in knowledge gaps with false information, knowing people are desperate for any information at all.

"It's supply and demand," said Keenan Chen, a disinformation researcher at the nonprofit First Draft News.

Because health officials are still investigating the clotting issue, and determining guidance about the vaccine, there isn't much trustworthy information the government or credible outlets can provide to fill that void.

UCLA's Roberts said the problem is further exacerbated because the country has become so divided over the pandemic in general.

Former President Donald Trump primed a portion of the country over the past few years to be skeptical of official sources of science information, including the Centers for Disease Control and Prevention. On Tuesday, he released a statement that included a false conspiracy theory about the Johnson & Johnson vaccine, claiming without evidence the decision was made to benefit rival drugmakers.

Now, Roberts said, whenever the CDC comes out with guidance about the Johnson & Johnson vaccine, health officials will be fighting ingrained doubts.

"Every time there's going to be a new bit of negative [vaccine] information or circumstances that sow doubt, it's like we're caught on the back foot and we have to come together again and push forward," Roberts said. "To call that an uphill battle ... I mean it's like a Mount Everest-sized battle. Uphill seems like an understatement."

Even after that guidance does come out, which officials said they hope will be in a matter of days, it's likely this development has ripple effects, especially driven by those who have made fear a business model and built their brands on vaccine skepticism.

First Draft's Chen noted that many of the actors who push vaccine disinformation also pushed election-related disinformation last fall and disinformation about other aspects of the pandemic.

"[For] the group of people whose business is about growing their audience on social media, and they monetize it, it's very easy for me to imagine that they would keep pushing this narrative, that they would come back and point to this pause," Chen said. "It would be hard for me to imagine that they would just stop — that they would just give up."

Copyright NPR 2021.