As per usual with this stuff it's nonsense.
The sequence homology shared the COVID spike protein and between syncytin-1 which is found in the placenta (and other tissues) is only 4 amino acids. Autoimmune antibody complexes generally only cause cross-reactions with sequence homologies that involve a higher number of amino acids. The entire syncytin-1 protein has 538 amino acids.
Also, if the mRNA that gets translated in the ribosome into a protein caused a cross over reaction due to similar sequence homology with syncytin-1, then getting the actual COVID virus would cause infertility in females without getting a vaccine.
Since there has been no evidence of widespread infertility from COVID itself, it stands to follow that the COVID vaccine would be even less likely to induce an autoimmune reaction leading to infertility.
Last edited: Apr 29, 2021