More than a thousand members of the medical community have signed onto an open letter to Spotify (SPOT  ) asking the platform to address the spread of COVID-19 misinformation by prominent podcast host Joe Rogan.

On Dec. 31, Rogan, former X-Factor host and stand-up comedian, had a discussion with guest Dr. Robert Malone about "mass formation psychosis", an unfounded theory that belief in the COVID-19 pandemic is akin to a mental disorder.

Initially, 270 doctors, scientists, and professors signed the letter, but more signatures have since been added.

Malone also stated on The Joe Rogan Experience (JRE) that the current anti-COVID efforts are similar to the anti-semitic beliefs held by Nazis during the Holocaust.

"What the heck happened to Germany in the 20s and 30s? Very intelligent, highly educated population, and they went barking mad. And how did that happen?" Malone said. "When you have a society that has become decoupled from each other and has free-floating anxiety in a sense that things don't make sense, we can't understand it, and then their attention gets focused by a leader or series of events on one small point just like hypnosis, they literally become hypnotized and can be led anywhere."

According to Forbes, "mass formation psychosis" is not a scientifically recognized phenomenon. Based on Malone's argument, the term is used to describe mob influence on perceptions and thoughts. Malone went on to claim that his opinions are being suppressed by the broader medical community (he was recently banned from Twitter (TWTR  ) for repeated violations of terms of service) and that the community is withholding information from the public about vaccine side effects. Malone failed to provide evidence to support this claim.

"Our government is out of control on this and they are lawless. They completely disregard bioethics, they completely disregard the federal common rule, they have broken all the rules that I know of that I've been trained on for years and years, these mandates of an experimental vaccine are explicitly illegal," Malone continued. Malone said that vaccine requirements "are explicitly inconsistent with the Nuremberg code, they're explicitly inconsistent with the Belmont report."

Malone may have called the vaccines "experimental", but this is misleading. Prior to use, the vaccine was approved by the U.S. Food and Drug Administration (FDA) for emergency use authorization.

Soon after the release of the episode, both Spotify and Rogan received widespread backlash, including the aforementioned medical community letter.

"The JRE has a concerning history of broadcasting misinformation, particularly regarding the COVID-19 pandemic," the letter reads. "By allowing the propagation of false and societally harmful assertions, Spotify is enabling its hosted media to damage public trust in scientific research and sow doubt in the credibility of data-driven guidance offered by medical professionals."

So far, most of the concern about misinformation has been directed at social media sites like Facebook (FB  ) and Twitter, but podcasts have the potential to do just as much damage. Members of the medical community like epidemiologist Katrine Wallace say they've received hundreds of messages and questions regarding the Malone JRE episode.

"Their friends and family were sending it to them as evidence that the vaccines are dangerous and that they shouldn't get it," Wallace told NPR. "It provides a sense of false balance, like there's two sides to the scientific evidence when, really, there is not. The overwhelming evidence is that the vaccines are safe and that they're effective."

For the last two years, JRE has landed the global top spot as Spotify's most popular podcast. In 2020, he reportedly signed exclusively with Spotify as part of a $100 million licensing deal.

Malone's appearance isn't the first time that Rogan has been accused of spreading COVID misinformation. In the past, Rogan himself has argued that young and healthy people don't need to get vaccinated and that those with COVID-19 should take Ivermectin, an approach the U.S. Food and Drug Administration (FDA) has explicitly warned against.

Rather than asking Spotify to kick Rogan off altogether, the medical professionals are asking the company "to immediately establish a clear and public policy to moderate misinformation on its platform." In the past, Spotify has claimed that it bans content that is "false, deceptive, or misleading" and "that may cause offline harm and/or pose a direct threat to public health."

According to Spotify, it has removed 20,000 podcast episodes from its platform for violating that rule since the beginning of the pandemic. Company CEO Daniel Ek told Axios last year that Spotify isn't responsible for what is said on JRE, comparing Rogan to musicians on the site.

"We have a lot of really well-paid rappers on Spotify too, that make tens of millions of dollars, if not more, each year from Spotify. And we don't dictate what they're putting in their songs, either," Ek said.

Researchers have studied the effect that podcasts can have on their listeners, questioning why this medium has yet to receive attention for misinformation.

"We're not talking about fringe ideas. These are the most popular podcasts in the United States," Evelyn Douek, a researcher with Columbia University's Knight First Amendment Institute, told NPR. "Wherever you have users generating content, you're going to have all of the same content moderation issues and controversies that you have in any other space."

In fact, researchers say that podcasts can be especially effective vehicles for misinformation due to the intimacy of the format.

"The podcaster is in your ear," Douek said. "It's a really unique relationship in that respect, and so the podcaster gains a level of authority and a level of credibility among listeners."

Fox News (FOXA  ) has pushed back against the open letter to Spotify, arguing that the fact that many of the signatories are not currently practicing doctors undermines its credibility. The letter states that signatories include professors and scientists.