GBS is an autoimmune disease. Your immune system attacks the nerve sheath.
Something like a vaccination or an infection can trigger it, but you don’t catch it like you would an infectious disease.
Its worse from a vaccine because vaccines contain ingreidients that are purposely put in there to cause a big surge in your immune system. They are classified as “adjuvants” and their purpose is to get an enhanced reaction from your immune system.
Vaccines when I was an infant are responsible for my horrendous allergies from then into adulthood. They were the worst during the years I was receiving vaccines. The more time thats passed by from those vaccine years, and building up my immune system with natural substances, the lesser they have become.
Allergies are an immune syytem response to things generally not considered something the body needs to fight, and these vaccines cause heightened immune responses. GBS is an extreme reaction and it starts attacking the bodys nerves and such, allergies can be developed because the hyped up immune system targets a normal thing like dust or pollen, a foreign body, and goes haywire by reacting to this generally non-harmful thing.