Cowpox was inoculated and propagated from arm to arm; and, in proof that the constitution was fortified against Smallpox, it was common to inoculate with Smallpox, which usually did not “take”; whereon the operator exclaimed, “Behold! the patient is insusceptible of Smallpox for ever!”
Such was the Variolous Test. It was to multitudes absolutely conclusive; and to question its validity was to exhibit a contentious and unphilosophic disposition.
What shall we now say concerning it?
First, that failures were numerous in Variolous Inoculation apart from Vaccination, and that it was not supposed that when a patient did not “take,” he was therefore insusceptible of Smallpox; nor even when he did “take,” that he was thereby rendered proof against Smallpox. So many of the successfully inoculated did subsequently fall victims to Smallpox, that Variolators at the end of last century were compelled to argue (like Vaccinators at the end of this) that Variolation was a guard, but not an absolute guard; and that when it did not altogether avert Smallpox, it modified and mitigated an attack. The excuse for failure was as artful as the motive was urgent: Variolation was too good a trade to be imperilled for lack of a little ingenuity.
Nevertheless, if we make full allowance on the score of frequent incapacity to receive Variolation, we have yet to explain, on a candid view of the whole evidence, how it was that in numerous cases Inoculation with Smallpox was ineffective after Inoculation with Cowpox.
“What can you urge against the Variolous Test?” was a frequent and imperious demand.
The explanation in general lay in the fact, that Variolation was attempted before the complete subsidence of the vaccine fever. The inoculation with Cowpox had set up a serious constitutional disturbance, and during that disturbance the Smallpox virus could not develop its malign energy. Let me show what I mean from the testimony of Jenner himself.
On 15th March, 1800, the Duke of York requested Jenner to proceed to Colchester to the 85th Regiment. Jenner was unable to go, and sent his nephew, George, instead, who had to report a complete failure. The reason of the failure was, that the entire Regiment, with women and children, had the itch! Jenner was then driven to the conclusion which, says Baron, “he adopted and invariably maintained to the last hour of his life, namely, that any cutaneous disease, however slight in appearance, was capable of interfering with the regular course of the Cowpox and of preventing it from exercising its full protecting influence.”[100]
Just so: and mark how the same logic applies to the Variolous Test, which “nobody could get over.” If any cutaneous disorder, however slight, could nullify Cowpox, was it not equally probable that the cutaneous disorder induced by inoculated Cowpox would nullify inoculated Smallpox until the effects of the Cowpox had time to subside? When the itch at Colchester was cured, then inoculation with Cowpox was found to be practicable. Thus worthless was the Variolous Test on Jenner’s own principle; yet with such evidence under his eyes and among his fingers, he failed to discern its significance. Nor apparently did he inquire whether the influence of Cowpox was perpetuated over specified periods of six months, nine months, one year, two years, and so on. As trader and adventurer, it suited him better to be not over inquisitive, and to avow boldly that his specific conferred life-long immunity from Smallpox.
Vaccinators at this day rarely refer to the once famous Variolous Test: to do so would be absurd. The fact of Re-Vaccination, of Vaccination after Vaccination at short intervals, proves, that whatever the influence of the operation, it is transient and not permanent; and the cases of Smallpox after Vaccination, and of Smallpox in its most malignant forms after Re-Vaccination, as if induced thereby, leave the Variolous Test, which so widely impressed and imposed upon our forefathers, an exploded piece of jugglery.