Homeopathy literature likes to compare Nosode remedies with traditional vaccinations, does this have any validity?
Simply stated: a nosode is a homeopathic remedy prepared from a pathological specimen. The only difference between a nosode and any other remedy, is the starting material. It could be blood, pus, any other body secretion or excretion, or even a diseased fragment of tissue, such as a growth. Rabies nosode for example, starts with the saliva of a rabid dog and is then "potentized".
Potentization in homeopathy explained:
Homeopathic potentization is a very specific form of potentization which was developed by Samuel Hahnemann. It involves serial dilutions by factors of 10 or 100 with succession.
So a nosode is prepared by extreme dilution in the way that a homeopathic remedy is prepared, but instead of starting from a compound with mystical healing properties, they are starting from some manifestation of the target disease itself, or something with a claimed connection to it.
Put aside the irony of "potentizing" meaning dilution to the point of non-existance of the original material for a moment, and wow, sounds a little bit like a killed or attenuated vaccine, so maybe there's something to this one?
Not so fast. A vaccine works by stimulating an immune response that the body remembers. This means that the vaccine needs to contain material that the body recognises in the same way that it recognises the disease organism (or its toxin in some cases). Such material might include the killed/inactivated organism itself, the live organism treated to be less virulent (attenuated), or parts of the organism that provoke a response in the immune system.
Preparation of a vaccine thus requires a very specific and non-zero amount of material that elicits a response from the immune system that mirrors that of the actual infection, while avoiding over-stimulation and actual disease.
Homeopathic potentization is specifically designed not to contain this material. The process of dilution involved in homeopathic preparation is designed to ensure no significant amount of the original material remains in the preparation. From the same site I referenced for the explanation of nosodes earlier:
The major difference between a nosode and an "orthodox" vaccine is of course the extremely small (if any) quantity of physical substance in a nosode. Remember, it is the "energy" pattern not the "substance" that does the job in a homeopathic remedy.
So since there is no remaining material to induce an immune response, these preparations are no different than other standard homeopthatic remedies - they are nothing but water, a placebo. They rely on the same woo and mystical sleight-of-mind that standard homeopathy uses.
Posit for a moment that nosodes did contain sufficient material to elicit an immune response. Since they are prepared from the actual infection itself (those that aren't prepared from irrelevant excretions) then the only effective response-inducing material would be the original disease-causing organism. Even attenuated live vaccines carry the risk of reversion to virulence or causing disease in immunocompromised subjects. In other words, such a preparation would simply infect the new host.