Egg yolks not shown to fight Covid-19

9 February 2023
What was claimed

Studies show egg yolks significantly increase immunity against Covid-19.

Our verdict

Researchers have found that inoculating chickens leads to Covid antibodies in their egg yolks. This doesn’t mean normal eggs have an anti-Covid effect when eaten, and we have no evidence that these antibodies can be used clinically.

What was claimed

The findings of these studies are linked to egg shortages.

Our verdict

Industry groups report that egg shortages in the UK and USA are being caused by increasing production costs and the spread of bird flu.

Full Fact has identified several Facebook posts that misinterpret research in chickens to make claims that eggs can be used to fight Covid-19. This claim has also appeared on Twitter.

The posts link this to recent egg shortages, suggesting they have been deliberately planned by people with an interest in maximising the number of deaths from Covid or profiting from the sale of medicines which help prevent or treat Covid.

The research cited in one post does not show that eating eggs is protective against or treats Covid-19. There is no evidence that recent increases in egg prices and shortages are due to deliberate suppression.

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What do the posts say?

One post claims “egg yolks can significantly increase the immunity against Coronavirus” and links this to egg shortages while implying the “bird flu outbreak” might not be the genuine cause of this. It links to studies published by the Multidisciplinary Digital Publishing Institute (MDPI) Viruses journal and International Immunopharmacology.

Another claims that “Multiple studies have now found that egg yolk antibodies neutralize Covid” and provides a list of examples of chickens and other poultry being “destroyed” in the US over an 18 month period. 

The poster sarcastically states they’re “suuuure it’s just coincidence”. Similar lists have been shared on Twitter. This post does not link to any specific studies.

What do the papers actually show?

In both studies mentioned, the researchers inoculated chickens against Covid-19 by injecting them with proteins from the virus and collected their eggs some weeks later. 

Both sets of researchers then extracted antibodies from the yolks of these eggs as well as from the eggs of a group of chickens that hadn’t been inoculated. They infected some cells with Covid-19 in lab conditions and tested the effect of adding in purified antibodies from both groups of chickens. In the MDPI Viruses study, blood from the chickens was also tested against the Covid-infected cells. 

They found that the yolk antibodies and blood from vaccinated chickens neutralised the simulated Covid infection, while the same substances from the control chickens did not. There are several other studies published using similar methods with similar results. 

The authors posit this as a potential route for making Covid-19 antibodies to use in humans. But this requires a lot more research. We have no data on how safe or effective these antibodies would be if given to animals, nevermind humans. So it would be a reach even to say that these antibodies—produced by vaccinating chickens then extracting and purifying them from yolks—could treat or defend against Covid in humans.

To claim that egg yolks in general can boost immunity goes completely beyond the findings of this research. 

Even if the eggs of inoculated chickens could provide some protection against Covid-19 to humans when eaten, that doesn’t mean eggs sold for consumption would have these benefits, because we wouldn’t know if the chickens who laid them had been infected with Covid-19. 

The British Egg Information Service (BEIS) told Full Fact that there is no program of Covid vaccination in UK chicken farms.

Egg shortage conspiracies 

The posts draw a conspiratorial link between these study findings and egg shortages. Egg prices have increased in some states in the US in recent months with the UK also facing shortages.

The American Egg Board told Full Fact that the USA and other countries “are dealing with what the World Organization for Animal Health and Food calls the largest outbreak of Highly Pathogenic Avian Influenza [HPAI] in history. There have been reports of temporary egg supply issues in scattered locations. Those shortages usually can be attributed to the detection of HPAI on a nearby egg farm and the emergency depopulation of that farm to help control spread.”

The BEIS told Full Fact that “the most critical factor is the increased costs that producers have faced over the past year.

“With costs soaring, many egg farmers have had no choice but to cease production rather than face the risk of losing money on every egg they produce. This, together with the added strain on supply due to the loss of some hens because of avian influenza, has led to the current shortage of eggs on retail shelves.” 

The National Farmers Union (NFU) poultry board chair James Mottershead said “Ongoing, soaring production costs are putting the British poultry sector under immense pressure.” The NFU was unaware of reports of British farms being burned.


Image courtesy of Polina Tankilevitch

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