The risk of spreading the contagion of smallpox by inoculating the disease was one of the objections to the practice raised by Wagstaffe in his letter to Dr Freind in 1722: “I have considered,” he says, “how destructive it may prove to spread a distemper that is contagious.” Still more explicit was Dr Douglass of Boston, New England, writing on 1 May, 1722: “I oppose this novel and dubious practice ... in that I reckon it a sin against society to propagate infection by this means, and bring on my neighbour a distemper which might prove fatal, and which, perhaps, he might escape (as many have done) in the ordinary way.... However, many of our clergy have got into it, and they scorn to retract[1160].” Within a few months there was a striking instance of the alleged danger in one of Maitland’s inoculations at Hertford, an inoculated child, with only twenty pustules, having been supposed the probable source of the natural smallpox in five domestics, of whom one died. The death of the Duchess of Bedford by the natural smallpox in 1724 happened “after two of her children were recovered of that distemper, which they both had by inoculation[1161].” That risk, however, was little made of in the controversy, although it may have been one of the tacit reasons that led to the total abandonment of inoculation during the ten or twelve years after 1728. On the revival of the practice after 1740, when the serjeant-surgeons, the physicians and the apothecaries were all making it a considerable part of their business among the richer classes, the danger from contagion was either non-existent or it was not realized. In 1754 the College of Physicians of London, by a formal minute, recommended inoculation as “highly salutary to the human race,” without one word of warning on the risk of contagiousness. That objection was raised again when Sutton’s practice in 1765-67 was drawing large crowds to be inoculated. He was put on his trial at the Chelmsford Summer Assizes in 1766 on a charge of spreading the contagion of smallpox, which was epidemic in the town; but the grand jury, charged by Lord Mansfield, threw out the bill. Sutton’s defence was to have been that he never brought into Chelmsford a patient capable of spreading the smallpox, that is to say, an inoculated person with smallpox enough on him to spread contagion[1162]. Shortly after came the controversy between Lettsom and Dimsdale as to inoculation of infants at their homes, which turned upon the risk of increasing the natural smallpox by a constant succession of artificial cases. Lettsom’s position was the same as Sutton’s, that the quantity of smallpox matter (he might have said the quality also) produced by inoculation was not sufficient to create an appreciable risk. As to the matter of fact, the quantity was indeed small: Sir William Watson declared that a single limb of an adult person in a moderate attack of the natural smallpox had as many pustules on it as all the seventy-four children, in one of his inoculations at the Foundling Hospital, had on their whole bodies. In the theory of contagion, an infinitesimal quantity is sufficient; but in reality it appears that contagion must be in excess to be effective, just as, in the nearest physiological analogy, fertilization seems to depend upon the copiousness of the pollen or seminal particles[1163].
The opposition to Lettsom’s project of general inoculations among the infants of the working classes in cities shows that the risk of contagion was made to serve at least an argumentative purpose. As to experience, Lettsom in 1778 declared that he knew no instance of contagion from that source during two years of inoculations among the poor of London[1164]. One writer of the time (1781) appealed boldly to the experience of sixty years: “Upon the first introduction of inoculation, physicians, divines, and innumerable other writers [who were they?] cried out that the infection would be spread, and the community suffer a greater loss; but after sixty years’ experience, we should expect those arguments, as well as the writers, had all died away, and that at this day the same stale dregs of ignorance and obstinacy would not be again retailed[1165].” The risk, however, was not altogether imaginary. Some cases of smallpox caught from the inoculated were known. In Vienna at that time the rule was to allow no inoculations except on groups of subjects isolated for the purpose. When Jenner, in 1798, enumerated the advantages of cowpox over smallpox for inoculation, in certain specified circumstances, one of his points was its non-contagiousness[1166].
The favourable reception of his project seems to have been determined more upon that point than upon any other. The theoretical risk of contagion from inoculated smallpox became at once an actual danger to the community when it was perceived that they had in “smallpox of the cow” a non-contagious variety. Jenner was not slow to use that growing sentiment so as to discredit the old practice. As early as 1802 he began to urge privately the statutory prohibition of smallpox for inoculation, and Wilberforce, among others, took the matter up publicly. The College of Physicians, having been asked by Parliament in 1807 to inquire into the causes that hindered the progress of Jenner’s inoculation, inserted the following paragraph in their report:
“Till vaccination becomes general, it will be impossible to prevent the constant recurrence of the natural smallpox by means of those who are inoculated, except it should appear proper to the Legislature to adopt, in its wisdom, some measure by which those who still, from terror or prejudice, prefer the smallpox to the vaccine disease, may in thus consulting the gratification of their own feelings, be prevented from doing mischief to their neighbours[1167].” The same year, in the court of King’s Bench, a medical practitioner was sentenced to fine and imprisonment for having neglected to prevent an inoculated person from communicating with others[1168].
Next year, 1808, a bill was brought into the House of Commons by Mr Fuller, with the following preamble: “Whereas the inoculation of persons for the disorder called the Smallpox, according to the old or Suttonian method, cannot be practised without the utmost danger of communicating and diffusing the infection, and thereby endangering, in a great degree, the lives of his Majesty’s subjects.”... This bill, which had clauses also for notification and compulsory isolation of smallpox cases, the churchwardens to be the authority, was not persevered with. The inoculators by the old method opposed it, and they were joined by Joseph Adams, who had been the first English writer to mention cowpox, in 1795, and had been a staunch vaccinist subsequently[1169]. In 1813 another attempt was made to restrict the practice of inoculating the smallpox on the ground of danger from its contagion, and to get cowpox substituted for it among the poorer classes. The Vaccine Board were the promoters, Lord Boringdon (afterwards Earl of Morley) having charge of the bill in the House of Lords. It was successfully opposed by the Lord Chancellor (Eldon) and by the Lord Chief Justice (Ellenborough), the latter contending that the common law was a better remedy than a statute against the nuisance of contagion from inoculated smallpox. Next year, 1814, Lord Boringdon brought in a new bill, which did not directly harass the inoculation interest, but made the rival method of cowpox obligatory upon the poor. Its provisions were ridiculed by Lord Stanhope, who got help from Lords Mulgrave and Redesdale to throw it out. Therewith ceased for many years the talk about the contagiousness of inoculated smallpox, together with the attempts in Parliament to enforce the rival inoculation. The next attempt, in 1840, was successful in making variolation a felony, and in throwing on the rates the cost of vaccinating the infants of the poorer classes. The danger of contagion from inoculated smallpox in 1840 was no greater than it had ever been, and it had never been appreciable among the things favouring an epidemic.
The common-law maxim, “sic utere tuo ut alienum non laedas,” which gained statutory force as against inoculation by the Act of 1840, was farther extended and specifically applied in the Act of 1853, which enforced the inoculation of cowpox upon all infants before they were three months old. Legislation, as we know, broadens down from precedent to precedent. Parliament in 1853 did not debate the preamble of the Bill, but accepted the principle established by the Act of 1840,—in the constructive sense that to leave infants without the inoculation of cowpox was, in effect, “to expose them so as to be infectious,” because they were sure to take smallpox, and so to become nuisances to others “unprotected” as well as (less obviously) to their cowpoxed neighbours.
Other effects of the epidemic of 1837-40 on medical opinion.
A second inoculation, except as a mere test of the first and within a few weeks thereof, was no part of the original 18th century teaching and practice. The theory of inoculation being based upon the familiar experience that we seldom have the same infectious disease twice in a lifetime, it was held that inoculation, if it were effective, was the giving of smallpox once for all, and that it could not really be given a second time unless the first inoculation had been ineffective. As soon as cowpox was recommended, it was remarked as a strange thing that this disease, according to current accounts of it, was actually acquired by milkers time after time. That fact in its natural history, said the Medical and Physical Journal of January, 1799, was “received with general scepticism merely on account of its improbability.” Dr Pearson was so troubled by the apparent inconsistency that he wrote to Dr Jenner in 1798 to ask whether it were really so; and although the latter confirmed the matter of fact, Pearson went on denying it, and did actually deny it as late as the Report of the Vaccine Pock Institution for 1803. Again, the report of the Whitehaven Dispensary for 1801, while it admitted the matter of fact, adverted to the anomaly in these words: “As we know from experience that the cowpock can be repeatedly introduced by inoculation, it appears remarkable that it can act as a preventive of a similar equally specific but more malignant disease.” Those were theoretical difficulties, which the practical minds of the profession did not stand upon. When we next hear of the possibility of having cowpox more than once, it is no longer an intellectual stumbling-block but is turned to account in the way of re-vaccination. Lapidem quem reprobaverunt aedificantes, hic factus est in caput anguli.
The practice of re-vaccination was usual on the Continent long before the English took to it. The reason of this was that a second inoculation of cowpox was not resorted to for the greater security of infants and young children, who were then the principal victims of smallpox in this country, but for the protection of adults, who made a great part of the subjects of the epidemics in other countries. There were so many adult deaths in the great Paris epidemic of 1825 that the news of it reads like the English references to smallpox in the time of the Stuarts. We obtain exact statistics of the ages in the 3323 fatal cases of smallpox in Paris from 1842 to 1851. Reduced to percentages they were as follows:
| All ages | 0-5 | 5-10 | 10-20 | 20-30 | 30-40 | Over 40 | ||||||
| 100 | 33·8 | 5·9 | 13·25 | 32·95 | 10·95 | 3·15 |