If you search “coronavirus" or “Wuhan" on YouTube -even in incognito mode, which removes customization from the search results -you’ll see high-quality content from verified news providers. But that doesn’t mean that hoaxes about the virus aren't being watched on the platform in huge numbers.

BuzzFeed News viewed a list on Monday of 500 of the most-watched YouTube videos featuring the keyword “coronavirus,” according to the social metrics dashboard BuzzSumo. Many of the top videos are from news agencies like Britain's Channel 4 News, the South China Morning Post, and BBC News. But that list also contains dozens of popular videos that feature unconfirmed or false information about the virus. In some cases, videos have earned millions of views with claims that the virus is an engineered bioweapon, that it originated from Chinese people eating “bat soup,” or that the death count is actually 10 times higher than reported. As of Wednesday, there were more than 45,210 reported cases of the virus, with 99% in China, and 1,118 deaths.

YouTube has waged a well-documented battle over the last year against the conga line of conspiracy theories that dance below the surface of the platform. Last February, the company demonetized anti-vax content. Last March, it announced it would be showing “information panels" -text widgets that offer debunks from the site’s fact-checking partners -on searches for topics “prone to misinformation.”

As of now, YouTube’s “coronavirus" search results are relatively free of that misinformation -a search returns a CDC warning, a liveblog about the outbreak from a trusted news source, and hundreds of videos from verified channels.

But the coronavirus is now putting those measures to the test -and in suppressing the fringe, the site has pushed it into smaller, denser pockets of viewers.

“We’re committed to providing timely and helpful information at this critical time, including raising authoritative content, reducing the spread of harmful misinformation and showing information panels, using WHO data, to help combat misinformation,” a spokesperson for YouTube told BuzzFeed News. “W​e also have clear policies​ that prohibit videos ​promoting medically unsubstantiated methods to prevent the coronavirus in place of seeking medical treatment, ​and we quickly remove videos violating these policies when flagged to us.”

In a statement issued after publication, a Facebook spokesperson said it is "working hard to stop the spread of coronavirus, including in groups."

The most-popular hoax on YouTube right now is that the coronavirus is a Chinese bioweapon. The most-shared video making this claim was viewed nearly 1.2 million times as of Tuesday. It was posted by a channel called US Military Times, which uses text-to-speech software to write news videos about territorial disputes in the South China Sea from an anti-Beijing point of view. US Military Times published two videos claiming the coronavirus was a bioweapon, the second of which was their most-watched video, receiving over 31,000 shares on Facebook. Its largest source of traffic coming from pro-Tibet Facebook groups, according to social metrics dashboard Crowdtangle. The bioweapon hoax has been rebutted by scientists.

Other channels pushing the bioweapon hoax are Geopolitics & Empire, which published a video titled “Francis Boyle: Wuhan Coronavirus Is an Offensive Biological Warfare Weapon" (150,000 views), and verified user Upper Echelon Gamers, which published “The CoronaVirus Conspiracy (Theory)” (198,000 views). Another hoax suggesting Microsoft cofounder Bill Gates was connected to the outbreak had been viewed around 150,000 times on YouTube and thousands of times on Facebook, largely in QAnon-affiliated Facebook Groups.

Videos using unconfirmed or debunked footage are also prevalent. A WeChat video clip of a Chinese nurse claiming 100,000 people had been infected was translated to English and is now going viral in multiple YouTube videos. According to WeChat users who spoke to BuzzFeed News last month, the clip has been so widely shared in China that the Chinese government sent out a message saying it was false.

The most popular video featuring the nurse, according to BuzzSumo, is “CORONAVIRUS Update by Chinese Nurse in Wuhan, China.” Posted to a channel called Ronald Daquipil, it has been viewed 850,000 times on YouTube. On Facebook, Daquipil’s video has been shared over 6,000 times. A Russian translation of the video, uploaded by a different channel, has been viewed around 800,000 times.

Another hoax circulating on YouTube suggested the coronavirus outbreak was caused by “bat soup.” It’s typically found in a montage of three video clips featuring a well-known Chinese influencer, eating bat meat at a hotel in Palau, a viral clip from Douyin (the Chinese version of TikTok), and a close-up of a bat in a bowl of broth. The most popular of these videos has been viewed 1.8 million times on YouTube.

Surpassing the bat soup hoax videos in popularity are the “collapsing" videos, in which alleged victims seem to collapse in public. There are hundreds of these, with the most popular one being viewed 1.1 million times. “What's Really Happening in Wuhan China | Coronavirus Outbreak | Symptoms and Tips" was posted by a channel called Astig Magaling, which seems largely to focus on the Philippines men's national basketball team.

The channel’s coronavirus clip is its most-watched video and has received a significant boost in Facebook groups, where it has been shared more than 5,000 times and promoted by a Chemtrails group and a group for people who believe the widely disproven claim that 5G cellular networks cause harmful radiation. As of Tuesday, the video, and one similar to it, had been viewed a combined 1.2 million times.

One user wrote in the Facebook Group Chemtrails Global Skywatch: “What are news isn't showing us. As I was watching this I was thinking bio weapon!”

“5G installed weeks ago...before this outbreak...” a second user commented. “Maybe have something to do with it.”