IgYs- that means they vaccinated these chickens. Then used the antibodies in the egg yolks from the vaccinated chickens to neutralize the virus in a test tube. In fact, it pretty much says exactly that in the last screen shot here. "IgY produced after immunizing chicken with a recombinant SARS-CoV-2 spike protein S1 subunit"- last sentence there.
IgYs- that means they vaccinated these chickens. Then used the antibodies in the egg yolks from the vaccinated chickens to neutralize the virus in a test tube. In fact, it pretty much says exactly that in the last screen shot here. "IgY produced after immunizing chicken with a recombinant SARS-CoV-2 spike protein S1 subunit"- last sentence there.