When I first began to learn of the dangers of vaccines, it was actually the measles/mumps/rubella or MMR that initiated my research. I spoke to a medical doctor who did not deny the possible link between this vaccine and injuries, and in fact spoke about an egg protein that was in the shots, where if an individual were allergic to eggs there could be dangerous results. I looked this up just now and there is documentation on the subject at the time of its discovery from the NACI and The Canadian Journal of Infectious diseases:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3327424/

Vaccines continue to have this protein in them to this day, which you can find on the website for the CDC (center for disease control and prevention):
https://www.cdc.gov/vaccines/vac-gen/additives.htm

The largest problem with this particular allergy is that the first round of MMR shots are given to a baby of six months. Which means there is no way to know whether they have an allergy to eggs since it's before a child would have ever consumed eggs. Not to mention there is a big difference between eating a bit of egg which then has to go through the digestive process, and having it injected directly into the bloodstream