My wife (MD) tells me that vaccine refers to anything that induces an immune response against a pathogen or disease. In this case the vaccine causes anti-EGFR antibody production
English is not my native tongue so I have some problem to parse your sentence. I prefer the writing in the publication cited above [0] even if it's probably the same meaning:
"CIMAvax-EGF is a therapeutic cancer vaccine composed of human recombinant EGF"
[0] https://aacrjournals.org/clincancerres/article/22/15/3782/79...
Here's the sentence restructured:
... vaccine refers to anything that induces an immune response against a pathogen or disease. Here is how that definition applies in this case: the vaccine causes the immune system to produce anti-EGFR antibodies.