What reliance may safely be placed on Vaccination as a means of exemption from Small Pox?

It may be affirmed, without hazard of contradiction, that no question connected with the physical well being of mankind involves considerations of more serious interest, or consequences of more vital moment, than that which has just been proposed. During the last quarter of a century, it has engaged a degree of attention, both from medical practitioners and from society in general, proportionate to the great importance of the subject; and though among the former, with very few exceptions, one pretty uniform opinion may prevail respecting the true value of the Jennerian discovery, I have reason to know, that many doubts and apprehensions still linger in the minds of not a few of the latter. These have been cherished or revived by circumstances, of a nature, it must be admitted, well calculated to shake their confidence in Vaccination as an absolute preventive of Small Pox; which, unfortunately for the cause, on its first introduction into practice, it was generally believed and asserted to be; but which subsequent experience has proved can no longer be contended for. I trust, however, to be enabled to prove, to the satisfaction of every impartial enquirer, that the value of Vaccination is not essentially diminished on that account; that an imperfect knowledge of its effects can alone have given rise to the doubts and apprehensions referred to; and that nothing is required for their entire removal but a more intimate acquaintance with the subject. It is the purpose of the present Essay, then, to bring under review the principal facts connected with the history of Small Pox and of Vaccination which, in any way, bear upon the question proposed; to arrange them in such order, and to place them in such lights, as may best elucidate the subject, and enable those, who have children not yet protected in any way from the infection of Small Pox, to form a clear and satisfactory judgment; a judgment unbiassed by prejudice, matured by a serious and candid consideration of the evidence that will be laid before them, and on which may depend life itself, or much that renders life desirable.

I have been led to believe that such an attempt may at this time prove of considerable service, in consequence of facts which have lately come under my own observation, and which have induced me to pay more attention than I had previously done to this singularly curious and interesting subject.

The facts to which I allude are—1st. The prevalence of Small Pox to a considerable extent in the town and neighbourhood of Newcastle, by which a number of deaths among children, who had not been vaccinated, has been occasioned.—2dly. The occurrence of the disease in many individuals, who had gone through the process of Vaccination; though in every instance as far as I have been enabled to ascertain, it has been so mitigated in the violence of the attack as to preclude any degree of danger, and has never run the regular course of the genuine Small Pox.—3dly. The impression, which these occurrences have made upon the minds of those in whose families they have taken place,—an impression not only unfavourable to Vaccination, but which has induced some to entertain the idea of again having recourse to inoculation for Small Pox.—And, 4thly. The occurrence of Small Pox itself a second time in an individual, who bore ample marks of having already gone through that disease, which she stated to have taken place naturally when young: this patient was a servant in a family where three instances had occurred after Vaccination, and, as in them, the disease was of a mild and modified character.

In all the cases of Small Pox after Vaccination which I have myself witnessed, or of which I have been enabled to obtain any distinct account, the disease has been of so mild a character, and so curtailed in its duration, that could it have been separated from the terrific name of Small Pox, it would have excited no apprehensions in the minds either of the patients themselves or of those around them. But it unfortunately happens that this disease is associated in our minds with so many terrific accompaniments (which were once indeed its constant attendants and consequences, and which belong to it in its natural form, but which, after the employment of Vaccination, have no existence whatever), that it is difficult for the mind to break through this association, and to feel satisfied that though Small Pox may still appear as an occasional visitor, yet, to the vaccinated, it is completely stripped of all that rendered it dangerous in its attack and serious in its effects.

I have had repeated opportunities lately of pointing out this satisfactory distinction to the parents of children who were affected with Small Pox, both after Vaccination and when no such protecting influence had been employed. The contrast between the characters of the disease, as evinced in these different individuals, was too striking not to carry immediate conviction to the minds of all present; and I believe it has been of considerable service in inducing many to have their children vaccinated, who would otherwise have omitted it altogether. These cases occurred among the lower orders of society; and I feel assured that this demonstrative proof of the utility of Vaccination will do more to remove the prejudices of these people than any abstract reasoning from facts of which they have not themselves been witnesses, however numerous and well authenticated. I should, therefore, strongly recommend it to every practitioner to take advantage of any opportunities that may be afforded him of pointing out this most marked distinction between the natural and modified Small Pox.