The next major statements on homeopathy and vaccination came with the classic textbooks of Close and Roberts in the first half of the 20th century. Neither spent a great deal of time on the issue, focusing more on the harm they saw resulting from vaccination in clinical practice. They disagree on whether vaccine therapy is an application of the law of similars. Close argued against vaccination on the grounds that it harms in the way it is administered. He did not go into the detail that Burnett devoted to the topic, but the message is quite clear: vaccination may be based on the concept of similars, but its method is faulty and dangerous.

Homeopathy is opposed to the methods of vaccine and serum therapy, although it is claimed by many that these methods are based upon the homeopathic principle. It grants that this may be true so far as the underlying principle is concerned, but opposes the method of applying the principle as being a violation of sound, natural principles of medication and productive of serious injury to the living organism. It has been proven experimentally and clinically that such methods are unnecessary, and that the results claimed by their advocates can be attained more safely, more rapidly and more thoroughly by the administration of the homeopathically indicated medicines in sub-physiological doses, through the natural channels of the body, than by introducing it forcibly by means of the hypodermic needle or in any other way. (Stuart Close, M.D., The Genius of Homeopathy: Lectures and Essays on Homeopathic Philosophy, p. 20)

Roberts espoused Hahnemann's later view that using disease tissue is isopathy, not homeopathy, and, thus, that the use of vaccines is not an example of the law of similars in action, but of the law of identities or isopathy (see Herbert A. Roberts, The Principles and Art of Cure by Homeopathy: A Modern Textbook, 1936, p. 16). Roberts saw vaccination as harmful and behind the plague of cancer already starting to emerge in his day.

George Vithoulkas, in his more modern, The Science of Homeopathy, presents a detailed explanation of why vaccination is a disease agent leading to the same shock to the vital force as a severe illness or allopathic drug. He states that vaccination is not homeopathic because it is not individualized. He does not argue specifically that the administration of a material substance is at fault, but this is implied. He sets out an interpretation of each of three possible reactions to vaccination: mild reaction, strong reaction, and very strong reaction. The mild reaction or no reaction means the vital force is not strong enough to resist the shock. The strong reaction suggests that the vital force is able to successfully overcome the shock of the vaccine but is then not "protected" by the vaccination (although this "protection" consists or an artificial suppression of the person's natural susceptibility to a disease agent). The very strong reaction means that there is a great susceptibility, but that the vital force is not strong enough to overcome the shock and serious damage occurs.

Vithoulkas argues that the cases of illness after vaccination that Burnett saw with smallpox are repeated by modern homeopaths with vaccines against rabies, influenza, typhoid, tetanus, etc. (George Vithoulkas, The Science of Homeopathy, 1980, p. 116). Vithoulkas cites one case where a woman was successfully treated and then received a smallpox vaccination for a foreign trip. Her case relapsed and did not respond any remedies until a dose of the nosode, Variolinum, made from smallpox, removed the blockage caused by the vaccination.

Vithoulkas, basing his opinions on Burnett's work, has given the clearest homeopathic statement on vaccination to date. Since Burnett, it has been widely accepted in homeopathy that the predisposition to vaccination shock lies in the sycotic miasm. Homeopathic practice essentially now recognizes that a patient may experience significant changes in health following vaccination and should be treated for "never been well since vaccination."

Another contemporary voice on vaccination within the homeopathic community is Dr. Richard Moskowitz, who concludes from his experience and observation:

It is dangerously misleading, and, indeed, the exact opposite of the truth to claim that a vaccine makes us 'immune' or protects us against an acute disease, if in fact it only drives the disease deeper into the interior and causes us to harbor it chronically, with the result that our responses to it become progressively weaker, and show less and less tendency to heal or resolve themselves spontaneously.