Smallpox quotes Medical Control ploys
Double Talk and Creative Logic. Medical advisers were using this ploy as far back as 1806. In that year Edward Jenner, the dubious "father of modern vaccinations," was under examination by a College of Physicians committee. Numerous members of the English population who had recently been vaccinated with Jenner's concoction, and who were therefore considered immune to smallpox, had caught the disease. Many were afflicted with painful skin eruptions and died. When the commonly relied upon denial ploy was no longer effective, it was revealed that "spurious," or phony, cowpox was the cause. As the number of vaccinated people afflicted with the disease grew, so, too, did public fear. How, Jenner was asked, could spurious cowpox be identified and avoided? Spurious cowpox, he explained, wasn't meant to describe irregularities on the part of the cow, but rather certain quirks in the action of cowpox on the part of the vaccinated. In other words, when the vaccinated recovered from the ordeal, and did not contract smallpox, the cowpox was genuine; otherwise it was spurious. Immunization Ploys-Are Parents Being Manipulated?by Neil Z. Miller
Jenner contended that every person who had had horse-grease cow-pox was protected against small-pox, but persons who had had the other kind of cow-pox were not protected, so that when he was confronted with cases where cow-pox had failed to protect, he said it was a spurious kind of cow-pox. A careful study of the evidence, as it is given in the writings of Prof. Crookshank, of William White. of Dr. Creighton, of Dr. W. Scott Tebb,†of Dr. Monckton-Copeman, of Dr. Alfred Russel Wallace, and many other writers, fails to show that there was anything worthy of the name of evidence in support of Jenner's theory that horse-grease cow-pox had a specific effect on the human body calculated to prevent infection by small-pox.  Vaccination and the State By Arnold Lupton MP.
In the Report we detect one good service, namely, the explosion of Jenner's fiction about Spurious Cowpox. When Vaccination was first brought forward, cases were adduced of Smallpox after Cowpox. Jenner at once asserted that the Cowpox in such instances must have been spurious, for Smallpox after genuine Cowpox was impossible; and Spurious Cowpox was thenceforward freely used to baffle inquirers and to account for failures. Spurious Cowpox served the ends of the Vaccinators magnificently, but by and by it began to have awkward consequences. Genuine Cowpox was said to be harmless —it was the Spurious that was ineffective or worked mischief; and the Inoculators plied the terror of Spurious Pox against Vaccination. It therefore became necessary to clear Spurious Cowpox out of the way, and Jenner, before the College of Physicians, pressed upon the point, "owned up," as Americans say, and authorised the following explanation—
Some deviations from the usual course have occasionally occurred in Vaccination, which the Author of the practice has called Spurious Cowpox, by which the public have been misled, as if there were a true and a false Cowpox; but it appears that nothing more was meant than to express irregularity or difference from that common form and progress of the vaccine pustule from which its efficacy is inferred.
Mark! Here was a third definition of Spurious Cow-pox by Jenner.
First, in the Inquiry of 1798, he described Spurious Cowpox as eruptions on the cow underived from horse-grease, producing no erysipelas when inoculated on the human subject, and without effect against Smallpox. True Cowpox was generated from horsegrease, and from horsegrease only.
Second, in the Origin of the Vaccine Inoculation of 1801 all reference to horsegrease was dropped for commercial reasons, whilst the existence of Spurious Cowpox was reasserted "as some varieties of spontaneous eruptions upon the cow."
Third, before the Physicians in 1807, he removed the spurious disease from the cow altogether, saying, nothing more was meant by Spurious Cowpox than variations in the form and progress of vaccine pustules on the arms of the vaccinated !
In short, to vary the phrase of Betsy Prig, "There never was no Spurious Cowpox." Slippery, very slippery, was the immortal Jenner.  The Story of a Great Delusion by William White
The most famous series of ulcerated cowpox arms happened among a rather poor and
querulous set of people in Thunderbolt Alley, Clapham, in the
fall of the year
1800 ; the parents of the poxed children were "much prejudiced, full of
invective, and refused to converse reasonably." The lymph was of correct
pedigree, and had been taken from the arm of a gentleman's
child ; only it had been taken after the crust began to form on the vesicle, and
it therefore represented a late type or a full cycle of cowpox, coming near to
that of cowpox on the cow herself or on the milker. The effects were erysipelas,
rapidly spreading ulceration, and sloughing ; a woman, aged thirty-five, had a
large, irregular, oval sore, with elevated edges of a livid colour. We now know
that such effects can be produced at will by systematically using lymph from a
late period of the pox, or, in other words, by using the infective matter in a
state fully representative of the cow's ulcerous affection.
But let us observe how such an untoward incident was explained away. Blair, the editor of the Medical Review, said that it arose from "this spurious sort, or from a violent matter derived from the cow." Dr. Lettsom, a leading physician, and a fussy or influential person among the charitable, rushed to the help of the endangered cowpox project with a letter dated 25th November, 1800 : "The disease," he assured the public, "was not cowpock, but morbid ulceration, originating from the purulent matter formed under the scab or dried pustule of the cowpock." Lettsom, whose writings prove him to have been something of a windbag, did not know what he was talking about. If the subject had been a suitable one for conundrums, Lettsom and such as he would have been in their element. When is the cowpox not the cowpox? Answer : (1) When it fails to protect from smallpox ; (2) When it produces "morbid ulceration."
Besides the apologetic plea of spurious lymph, the excuse was sometimes put forward that the smallpox ensuing was not smallpox but something else. Thus, Bevan of Stoke-on-Trent sends two cases of children who had been vaccinated on the 12th of January because their mother had confluent smallpox, and had themselves sickened for that disease on the 23rd and 24th respectively, the one having sixty pustules on the 28th, and the other, twenty on the 29th, "exactly like smallpox in every respect." To this perfectly credible recital the editor of the medical journal coolly appends a note : "We think this eruption was not variolous." The common explanation of an eruption of the milder sort was that it was really chickenpox, even if the circumstances of infection should have suggested smallpox. At a later period that excuse grew into the doctrine of varioloid or "modified" smallpox, especially in connexion with the epidemic in Scotland in 1818, described by Thomson. In the Vienna school the same mode of reasoning was carried so far that varicella, the learned name of chickenpox, actually came to be used as the equivalent of discrete smallpox or varioloid, or "modified " smallpox (e.g., in Hebra's writings), and continued to be so used down to recent times.
Other and more subtle excuses for failure were made in Germany (see chapter 9.); but the two stock English pleas were, either that the lymph was spurious, or that the ensuing disease was not smallpox. The nearest approach to the refinements of the Germans occurs in a case in which Sir Joseph Banks played a part. Being personally interested in a child in the country who had caught smallpox six months after vaccination, he wrote to the medical attendant, Dr. Harrison, of Horncastle, and received the following explanation : The child had been vaccinated successfully, and others in the house had in turn been vaccinated from her. Now these latter did not intake smallpox on the occasion when their vaccinifer did, although they were in the same house ; "hence it appears that Fanny communicated a security against the smallpox to others, although she herself remained liable to its influence." With this mystical reasoning the good president of the Royal Society would appear to have been well content, for he allowed the letter which his inquiry had elicited to be published in the Medical Journal.1
Such, then, was the programme of excuses which catme to be generally adopted for the failure of cowpox.  Jenner and Vaccination A Strange Chapter of Medical History by Charles Creighton M.D.