8. The Small Pox, when communicated by inoculation, is probably as secure a preventive of any future attack of the disease as when it has taken place naturally.
9. Notwithstanding the undeniable advantages which accrued to those who passed through the process, it was, nevertheless, the direct effect of inoculation, by multiplying the sources of infection, materially to encrease the aggregate mortality occasioned by Small Pox.
CHAP. III.
Such having been proved to have been the destructive consequences of Small Pox, previous to the introduction of Vaccination, we are fully prepared to enter upon the second query proposed,—What influence has Vaccination exerted over these consequences—1. by extensively superseding the cause—and 2. by essentially interfering with the effect?
The name of Dr. Jenner is too intimately associated with the subject of Vaccination to admit of the latter being referred to without some allusion being made to the former; and I should ill testify my sense of the truly valuable blessing which Jenner has been the means of conferring upon mankind, were I altogether to omit any expression of my admiration of the superior perception which enabled him to infer the probable consequences of facts, which must have been long familiar to hundreds without having given rise to any important suggestion, and of the zeal and ability with which he prosecuted his enquiries on the subject, or my high esteem for the generous disinterestedness with which he made known to the world his most useful discovery. “It will,” (to use the words of Sir Gilbert Blane,) “in the eyes of future ages, be deemed an epocha in the destinies of the world, and one of the highest boasts of the country in which it took its rise, with a sense of unrequitable obligation to the individual who first disclosed and promulgated the secret, by drawing it from the dark recesses of rural tradition, and rendering it available to the whole human race.”
It is not, however, my intention to enter into any detail of the mode in which Vaccination originated, or of the circumstances which accompanied its introduction into practice. It will suffice to state, that its supposed efficacy in preventing the occurrence of Small Pox, was founded upon repeated observation, that the milkers employed in the great dairies of Gloucestershire and the neighbouring counties, who became affected with a disease which prevailed among the cows, and to which the name of Cow Pox had been given in consequence, were very generally rendered insusceptible of the Small Pox infection, even when attempted to be communicated by means of inoculation. Dr. Jenner put this fact to the test of repeated experiment, and finding it thus confirmed, proposed introducing the Cow Pox into the human constitution artificially, as a means of securing it against the dangers of Small Pox, and, in the end, of entirely exterminating the latter disease; for it must appear very evident, that if every individual could in any way be rendered incapable of being infected by Small Pox, the infection itself must necessarily become entirely extinct.
In prosecuting my enquiries into this part of my subject I shall, as far as may be, confine myself to an examination of facts calculated, as I conceive, to remove every reasonable doubt respecting the true value of Vaccination.
The first essential fact, to which I would direct the attention of my readers, is the very striking diminution in the number of deaths from Small Pox, which has taken place within the bills of mortality of London, since the introduction of Vaccination. This diminution is equally remarkable, whether we refer to the actual number of deaths from this cause, or to the relative proportion which they bear to the whole amount of deaths occurring in any given year or number of years. Thus taking the averages calculated on periods of five years each, as is shewn in the table (No. 2), it will appear evident not only that the amount of diminution has been most gratifying and satisfactory, but that, in proportion to the increasing employment of Vaccination, it has been regularly progressive; so that the number of deaths from Small Pox, instead of amounting to one in ten of the whole, as was the case for the ten years which preceded the introduction of Vaccination, has during the last ten years, actually amounted to less than one in twenty-eight, or little more than one-third of the former proportion.
If we compare the number of deaths from Small Pox, which took place during the twenty-five years (from 1784 to 1798 inclusive) which immediately preceded Vaccination, amounting to 46,996, with the number which has taken place during the twenty-five years which have elapsed since its introduction (from 1799 to 1823 inclusive), amounting to 25,869, we shall find that an actual diminution has taken place of no fewer than 21,127, or nearly one half of the whole. It may, therefore, be confidently assumed, even upon this very simple calculation, that a number of lives equal to this diminution has been saved by Vaccination, within the bills of mortality alone. And as this diminution in the amount of mortality from Small Pox is going on in a progressive ratio, it is probable that the next twenty-five years will afford a yet more striking result.