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Sara Swann
By Sara Swann January 26, 2024

Claim that Chinese scientists created 100% fatal COVID-19 strain misconstrues study’s findings

If Your Time is short

  • Researchers in China recently released a study, which has not been peer-reviewed, that tested the GX_P2V coronavirus on genetically engineered mice. Although GX_P2V belongs to the coronavirus family, it did not originate from SARS-CoV-2, which causes COVID-19.

  • The mice were genetically engineered to express a protein that SARS-CoV-2 uses to enter human cells. All four mice infected with GX_P2V died in the experiment, but the researchers said this result doesn’t apply to humans.

  • The researchers did not create the GX_P2V coronavirus. Since its discovery in 2017, GX_P2V, like all coronaviruses, has adapted and produced variants. The researchers cloned a cell-adapted variant of GX_P2V to use in their study.

  • How does PolitiFact decide our ratings? Learn more here.

Should we panic? Social media users might after seeing online claims that researchers in China are concocting a disease that’s deadlier than COVID-19.

Chinese scientists "created (a) new COVID-19 strain (with) 100% fatality," a Jan. 21 Instagram post’s caption read. "It’s not like biological (warfare) is real, so nothing to see here folks."

The Instagram post showed a report from conservative news outlets NTD News and The Epoch Times that claimed the coronavirus strain was "biologically lab made." The report said all the mice tested in the study died from the infection and suggested this "mutant coronavirus strain" could also kill humans.

Another Instagram post, shared Jan. 22, made a similar claim about Chinese scientists creating a "mutant covid strain (with a) 100% death rate."

"When they injected this new strain into humanized mice, all of them died within eight days," the person in the video said. "They created an even more deadly variant."

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The post then linked this study to discussions by the World Economic Forum, a frequent target of conspiracy theories, about preparation for Disease X. But the two aren’t related. Disease X refers to any undiscovered human disease that could lead to an international epidemic. It’s not proof world leaders are planning a new pandemic.

(Screengrab from Instagram)

These Instagram posts were flagged as part of Meta’s efforts to combat false news and misinformation on its News Feed. (Read more about our partnership with Meta, which owns Facebook and Instagram.)

Some news outlets, including the New York Post, NewsNation and GB News, also ran headlines about the study that warned of a new fatal COVID-19 "strain."

But virology experts — both involved in and independent of the study — said social media posts and news headlines have misconstrued the findings.

Dan Wilson, a molecular biologist and science communicator not involved in the study, said the panic the social media posts incited is unfounded. Wilson hosts "Debunk the Funk with Dr. Wilson," a YouTube show that covers science misinformation.

"This is important research that simply highlights the threats that already exist in nature and attempts to learn about them before they become an immediate problem," said Wilson, who is also a senior associate scientist at Janssen, one of the pharmaceutical companies that developed a COVID-19 vaccine.

Animal study of virus similar to SARS-CoV-2 is "not applicable" to humans

In the preprint study, published Jan. 4, 10 researchers in Beijing and Nanjing, China, tested a type of coronavirus to see whether it could cause disease in laboratory mice. As a preprint, this study has not undergone peer-review, in which other scientists with expertise comparable to the researchers read the research and evaluate its methodology and validity.

The study’s researchers did not "create a new COVID-19 strain," as social media posts and news articles claimed. They were working with a different coronavirus called GX_P2V, which the study said was discovered in 2017 in pangolins, sometimes known as scaly anteaters.

GX_P2V is similar to SARS-CoV-2, which causes COVID-19; both belong to the large coronavirus family. But experts said GX_P2V is not a COVID-19 strain, variant or mutation.

Coronaviruses are known to mutate rapidly, producing viral variants. Since its discovery, GX_P2V has adapted over many generations in cell culture, the study said.

For this study, the researchers cloned a cell-adapted variant of GX_P2V.

Scientists often use "humanized" mice, or mice engrafted with something from humans, in experiments because they can act as models for research on human diseases. In this case, the study said, the humanized mice were genetically modified to express ACE2, the protein SARS-CoV-2 uses to enter cells in the human body. Without this mutation, the mice can’t become infected, experts said.

Beijing University of Chemical Technology professor and researcher Lihua Song, who was involved with the study, told PolitiFact the research originally intended to test the mice’s immune responses to the virus, "not to mimic human infection."

All four mice infected with GX_P2V unexpectedly died within eight days, likely because of severe brain infection, the study said.

Typical mice and human brains have low levels of the ACE2 protein, Song said.

But the humanized mice used in this experiment, which Beijing SpePharm Biotechnology Co. developed, had a "high expression" of ACE2 in their brain and lung tissues, which made them more susceptible to infection, Song said.

"The experimental results obtained with this model cannot be extrapolated to suggest similar infections in humans," Song said.

Some of the misinformation around this study seems to have come from the study itself. The preprint study’s first version incorrectly stated there is a "spillover risk" of GX_P2V into humans, Song said.

"We have no data to support this," he said.

After misinterpretations of the study spread online, Song posted Jan. 17 on the research forum Science Cast to clarify the findings. On Jan. 21, Song and his colleagues released an updated version of the study that was, Song told PolitiFact, "revised fundamentally to state the fact that these animal results are not applicable to humans."

The updated study said GX_P2V could help determine whether vaccines and drugs can effectively protect against COVID-19 and its future variants. For example, researchers could vaccinate the humanized mice for COVID-19 and then infect them with GX_P2V to evaluate whether a COVID-19 vaccine could protect against other coronaviruses, Song said.

Our ruling

Instagram posts claimed Chinese scientists "created (a) new COVID-19 strain (with) 100% fatality."

Researchers in China cloned and tested a cell-adapted variant of GX_P2V, a coronavirus that was discovered in 2017, on humanized mice. The researchers did not "create" GX_P2V and it did not originate from SARS-CoV-2, which causes COVID-19.

All four mice infected with the virus died in the experiment, but researchers said the findings don’t apply to humans.

We rate this claim False.

Our Sources

Instagram reel (archived), Jan. 21, 2024

Instagram reel, Jan. 22, 2024

Email interview with Lihua Song, a professor at Beijing University of Chemical Technology and one of the researchers involved with the study, Jan. 24, 2024

Email interview with Dan Wilson, a senior associate scientist at Janssen and host of the YouTube show "Debunk the Funk with Dr. Wilson," Jan. 24, 2024

Email interview with Michael Imperiale, professor emeritus of microbiology and immunology at the University of Michigan, Jan. 25, 2024

bioRxiv, "Lethal Infection of Human ACE2-Transgenic Mice Caused by SARS-CoV-2-related Pangolin Coronavirus GX_P2V(short_3UTR)," Jan. 4, 2024

bioRxiv, "An infection and pathogenesis mouse model of SARS-CoV-2-related pangolin coronavirus GX_P2V(short_3UTR)," Jan. 21, 2024

Science Cast, Lihua Song's response to misinterpretations of study, Jan. 17, 2024

The Conversation, "What is the ACE2 receptor, how is it connected to coronavirus and why might it be key to treating COVID-19? The experts explain," May 14, 2020

Taylor & Francis Online, "Induction of significant neutralizing antibodies against SARS-CoV-2 by a highly attenuated pangolin coronavirus variant with a 104nt deletion at the 3'-UTR," Dec. 18, 2022

The Jackson Laboratory, "Why humanized mice?," July 21, 2020

The Jackson Laboratory, "K18-hACE2 transgenic mice," accessed Jan. 25, 2024

National Library of Medicine, "A SARS-CoV-2-Related Virus from Malayan Pangolin Causes Lung Infection without Severe Disease in Human ACE2-Transgenic Mice," Jan. 23, 2023

The Centers for Disease Control and Prevention, "SARS-CoV-2 Variant Classifications and Definitions," Sept. 1, 2023

National Institute of Allergy and Infectious Diseases, "Coronaviruses," March 22, 2022

The New York Post, "Chinese lab crafts mutant COVID-19 strain with 100% kill rate in 'humanized' mice: 'Surprisingly' rapid death," Jan. 16, 2024

NewsNation, "Chinese scientists experiment with fatal mutant COVID strain," Jan. 17, 2024

GB News, "China told to IMMEDIATELY stop new tests on mutant Covid strain with '100% fatality rate'," Jan. 17, 2024

PolitiFact, "What is Disease X? How conspiracy theorists hijacked pandemic preparedness," Aug. 10, 2023

PolitiFact, "Disease X isn’t being planned at World Economic Forum meeting," Jan. 18, 2024

PolitiFact, "This World Economic Forum video doesn’t prove any COVID-19 conspiracy. It employed an analogy.," Sept. 15, 2023

PolitiFact, "The World Economic Forum is not planning to seize control of everything through ‘the Great Reset’," Sept. 28, 2023

Snopes, "Did Chinese Scientists Experiment With 'COVID-Like' Virus That Killed 100% Of Mice?," Jan. 19, 2024 

YouTube, "Debunk the Funk with Dr. Wilson," accessed Jan. 25, 2024

U.S. Food and Drug Administration, "Janssen COVID-19 Vaccine," June 2, 2023

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