Study doesn’t prove egg yolks protect against COVID-19

February 6, 2023 GMT
FILE - Eggs are displayed on store shelves at a local grocery store in Chandler, Ariz., Jan. 21, 2023. Social media users are misrepresenting a 2021 study about antibodies in chicken egg yolks to push a conspiracy theory tying the current egg shortage in the U.S. to the COVID-19 pandemic. Here are the facts. (AP Photo/Ross D. Franklin, File)
FILE - Eggs are displayed on store shelves at a local grocery store in Chandler, Ariz., Jan. 21, 2023. Social media users are misrepresenting a 2021 study about antibodies in chicken egg yolks to push a conspiracy theory tying the current egg shortage in the U.S. to the COVID-19 pandemic. Here are the facts. (AP Photo/Ross D. Franklin, File)

CLAIM: A protein naturally found in egg yolks protects against COVID-19 in humans, which is why there is an egg shortage.

AP’S ASSESSMENT: False. The claim misrepresents a 2021 study by a group of Chinese researchers who immunized hens with part of the coronavirus spike protein in order to extract antibodies from yolks in the hens’ eggs. Experts say these antibodies would not be very useful for humans, nor do eggs naturally provide these antibodies. Further, the current egg shortage is caused by an avian flu outbreak leading to reduced egg production and a rise in prices.

THE FACTS: Social media users are sharing a conspiracy theory about the origin of the current egg shortage in the U.S., misrepresenting a 2021 study to link the scarcity to the COVID-19 pandemic.

“It never seems to fail that what there is a shortage of, or what is deemed unhealthy… often holds the most powers in the current situations,” wrote one Instagram user who shared a screenshot of the study, which was archived in the National Library of Medicine.

“PREVENT’S COVID! Do you understand why gov’ts are messing with chicken feed & destroying egg farms!” another user posted on Twitter alongside the same screenshot. The post references other debunked claims that chicken feed is being altered to reduce egg production and that fires are being set at food plants to create shortages.

While the posts imply a link between the study and the current egg shortage, the two have no relationship to each other, experts say.

“Eating eggs which have antibodies against SARS-CoV-2 is completely useless against COVID-19,” said Peter Palese, a microbiology professor at Mount Sinai’s Icahn School of Medicine who has conducted similar research. “Such antibodies taken orally are right away digested in our digestive tract.”

The study — titled “Chicken Egg Yolk Antibodies (IgYs) block the binding of multiple SARS-CoV-2 spike protein variants to human ACE2” — was published in January 2021 by a group of researchers affiliated with the Institute of Biomedical Engineering and Technology in Suzhou, China. The researchers did not respond to multiple requests for comment.

The study describes how antibodies against the coronavirus spike protein were isolated from chicken egg yolks, according to Palese. However, this was achieved by first immunizing hens with a portion of the spike protein. The antibodies were not naturally occurring in the hens, nor would they have a profound impact on COVID-19 in humans, according to Palese.

“Such antibodies are good laboratory reagents but are no good for injecting into humans,” Palese wrote in an email to The Associated Press. “Humans would right away make antibodies against the chicken antibodies and prevent the further use of such a medication.”

Daria Mochly-Rosen, a professor in the Stanford University School of Medicine’s department of chemical and systems biology, confirmed that the hens first need to be immunized with a protein derived from the virus for the antibodies to be present in their egg yolks. Even then, she said, the antibodies need to be purified from the raw eggs.

“If you cook the egg the antibodies are useless,” Mochly-Rosen added.

In a similar study published in the journal “Viruses” last year, a team of researchers “hyperimmunized” hens by injecting them with vaccines made with COVID-19 proteins, then collected the hens’ eggs to obtain antibodies called Immunoglobulin Y, or IgYs. Those antibodies were used in a laboratory to perform virus neutralization tests, said Dr. Rodrigo Gallardo, a professor of poultry medicine at the University of California, Davis’ school of veterinary medicine who contributed to the research.

The team found that the antibodies were capable of neutralizing virus action in cells in-vitro, however, Gallardo emphasized that the hens were vaccinated first, and that not all eggs contain antibodies that can neutralize COVID.

“Even though all hens and egg yolks contain IgY’s, in order to obtain those that neutralize SARS-CoV-2 you need to immunize (vaccinate) hens with a vaccine containing the virus, proteins, subunits or mRNA from the virus,” Gallardo said. “Not all eggs will contain these specific IgY’s that neutralize SARS CoV-2.”

Gallardo confirmed that the source of the current egg shortage is known to be caused by an outbreak of Avian Influenza H5N1 that has led to the losses of tens of millions of poultry and caused egg production to slow. The outbreak, combined with soaring feed, fuel and labor costs, has led to U.S. egg prices more than doubling over the past year,

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This is part of AP’s effort to address widely shared misinformation, including work with outside companies and organizations to add factual context to misleading content that is circulating online. Learn more about fact-checking at AP.