Probably should look around a little bit before advancing to the “removing all doubt” portion of that old adage.
https://www.medscape.com/viewarticle/944936?form=fpf
Are Vaccine Allergies Common?
Vaccine allergy is rare. The cause of these rare allergic reactions to vaccines is usually not the antigen but an excipient — additives that may include antibiotics, preservatives, or adjuvants. Meat proteins (gelatin and, rarely, alpha-gal) have also been identified as causes of IgE-mediated reactions in vaccines with higher gelatin content (MMR and VZV). Therefore, in some instances, atopy (especially food allergy) may be a risk factor for reactions to certain vaccines.
Gelatin does exist in many vaccines (MMR is one of the most common vaccines out there), but not in the main coronavirus vaccines. It’s not known if it is in Johnson and Johnson.