SANITARY COMMISSION. E. REPORT OF A COMMITTEE APPOINTED BY THE SANITARY COMMISSION TO PREPARE A PAPER ON THE VALUE OF VACCINATION IN ARMIES. SECOND EDITION. The attention of the Sanitary Commission has been called to the fact that most of our Army Surgeons now in the field are unavoidably deprived of many facilities they have here- tofore enjoyed for the consultation of standard medical au- thorities. It is obviously impossible to place within their reach anything that can be termed a medical library. The only remedy seems to be the preparation and distribution, among the medical officers of the army, of a series of brief essays, or hand-books, embodying, in a condensed form, the conclusions of the highest medical authorities in regard to those medical and surgical questions which are likely to 2 present themselves to surgeons in the field, on the largest scale, and which are, therefore, of chief practical im- portance. The Commission has assigned the duty of preparing papers on several subjects of this nature to certain of its associate members, in our principal cities, belonging to the medical profession. The following paper on the Value of Vaccination in Armies belongs to this series, and is respectfully recommended by the Commission to the attention of medical officers. FRED. LAW OLMSTED, Secretary. Washington, December, 18G1. REPORT. In view of the possible occurrence of smallpox as an epidemic in our camps, and of the well established fact of its great contagiousness, even under the most favorable circumstances, the question of protection against its ravages commended itself, with great propriety, to the “Sanitary Commission.” At their request the undersigned have pre- pared a short digest of the more recent authorities upon the subject of protection, which, with the sanction of the “Commission,” they respectfully submit to the medical officers in the service of the government. It is unnecessary to enter into any history of vaccination ; that, it is presumed, is familiar to all to whom this paper is addressed ; but the question of its protective influence and the various circum- stances modifying it, together with the results of revac- cination in large bodies of men, may perhaps be profitably discussed. The fact cannot be concealed that a feeling of doubt has arisen in the minds of some (chiefly non-profes- sional persons, it is true) in regard to the efficacy and protec- tive power of vaccination, together with an ill-defined fear that some malign influence may through its agency be intro- duced into the bodies of those receiving it. To such the strongest argument that can be presented, and the unanswer- able one, is that which, in the words of Jenner, “is engraved with the point of the lancet.” It may not be out of place, however, to recall the analogy, if not similarity, of a disease which prevails among several of the lower animals and in man, and its communicability and protective influence from one to the other. The “grease” in the horse and the vaccine disease or cowpox are believed to be the same disease with smallpox in man. And as one attack of smallpox is known to be an almost certain protec- 4 tion against subsequent attacks, so may the artificial produc- tion of a modified smallpox in man present an immunity from further visitations. “It is -well known,” says Mr. A. B. Steele,* “ that Jenner was strongly impressed with the conviction that cowpox is neither more nor less than a mild form of smallpox, and this prediction has been completely verified by subsequent observations.” In the report of the Vaccination Committee of the British Medical Association + the following conclusions, drawn from information derived from various sources, ma}r be found : First. That it has been proved that cattle, in many ages and in different countries, have been affected with smallpox. Secondly. That the disease among the inferior animals has simultaneously existed with the smallpox in man, and pursued its victims through every country of the globe. Thirdly. That it appeared among cattle in England in 1745, and again in 1770, and continued its ravages up to 1800 ; and that the local remains of this epizootic occasionally still show themselves with considerable severity. Fourthly. When the disease appears among the inferior animals in a malignant form, it produces, by inoculation, a •disease of a similar severity in man. Fifthly. That as man has received this affection from the cow, so likewise has the cow received it from man. Sixthly. The direct inoculation of the cow with human -smallpox has produced a mild and mitigated disease, and that such a disease reproduced by inoculation in man, accords entirely in its character, its progress, and its protective influence, with the variola vaccinia as described by Dr. Jenner, thus irresistibly proving his fundamental proposi- tion, that cowpox and smallpox are not bona fide dissimilar, but identical, and that the vaccine disease is not the pre- ventive of smallpox, but smallpox itself, the virulent and contagious disease being a malignant variety.^ c Liverpool Med. Chir. Jour., July, 1858. fTraus., vol. viii. % Strong evidence in support of this proposition is found in the fact that cattle who were put to graze in a field where the bedclothes of smallpox patients were exposed to the air, contracted the disease, and presented not 5 The late Samuel Forry, M. D., of New York, formerly of the U. S. army, remarks : “That the opinion has received a very remarkable corroboration in the recent experiments of Mr. Ceely, of England, which seem to prove that not only may the cow be inoculated with variolous matter, but it may thus be converted into vaccine. Two experiments made by Dr. Thiele, of Kasan, in Russia, appear to confirm the same result. In 1836 he inoculated some cows on the udder with the matter of smallpox, which produced vesicles bearing all the characters of the true vaccine vesicle in those animals. During seventy-five successive transmis- sions in the human subject of the vaccine virus thus pro- duced, it appeared always to retain its normal character. In 1838 M. Thiele repeated this experiment with the same success.”* The subject of vaccination, whether in civil or in military life, may be considered under three heads : 1. Does vaccina- tion afford positive protection to those exposed to the variolous contagion? 2d. Is that protection permanent, or is it modified by any circumstances ? 3d. If not permanent, is revaccination a preventive of the disease ? 1. Does vaccination afford positive protection to those exposed to variolous contagion ? In considering this first question we are struck with the vast amount of evidence which has been accumulated in its favor. It finds no parallel in any other scientific investiga- tion. The committee have endeavered to select such only as seemed most conclusive, and have drawn largely from both domestic and foreign sources. The late Dr. S. Forry, in the Boylston Prize Essay, 1844, only the characteristic eruption, but well-marked constitutional symptoms. (Wilson on Diseases of the Skin, 4th Am. ed., p. 453.) Dr. Waterhouse, of Cambridge, Miss., in a letter to Dr. Jenner, details the communication of the disease to cows by the hands of milkers who were suffering from variola ; and Dr. Sonderland, of Bremen, communicated the smallpox contagion to cows by covering them with sheets between which persons fatally affected with small- pox had lain. ° Boylston Prize Essay. 6 says that, “as respects the protecting power of vaccination against smallpox, it is, ivlien perfect, as complete a protec- tion as any other prophylactic known to man.” The report of the committee of the Medical Society of Philadelphia, by Drs. C. J. Coxe, Condie, and C. D. Meigs, contains the remarkable fact, that during the prevalence of a most malignant and fatal smallpox in 1827, but one well ascertained death from that disease, among 80,000 vacci- nated, came to the knowledge of the committee. Drs. J. Bell and J. K. Mitchell* report that of 248 cases of variola and varioloid treated at the Smallpox Hospital, 155 were unprotected, of whom 85 died ; 04 were vacci- nated, of whom but a single one died ; 9 were inoculated, of whom 3 died ; and of the 13 whose condition was un- known, none died.t In an epidemic which prevailed from 1825 to 1827, in Copenhagen, of those who had been vaccinated 428 were attacked ; and in 26 of these all the symptoms of genuine variola were evinced, but only two of them died.| In Holstein, from 1801 to 1822, 234,959 were subjected to vaccination, and only two individuals, even two years sub- sequent to this, had during all that time been affected with smallpox. In the kingdom of Denmark, during the same period, only one individual among 447,005 vaccinated had been attacked by modified variola. Dr. G. B. Wood§ says that “vaccination affords the best attainable security to life, greater even than that accruing from a previous attack of smallpox ; that, with due care, it will serve as an effectual safeguard in individual cases almost without an exception. In the course of my practice, though I have seen much of the disease, I have lost but one patient after vaccination, and in that instance death occurred, not from the violence of the varioloid disease, which was mild, but from the supervention of inflammation of the brain, consequent on the peculiar state of the patient’s constitu- ° N. A. Med. and Surg. Journ., vol. ii, 1826. ■)• Bell and Stokes’ Practice. | Forry. § Practice, vol. i. 410. 7 tion at the time. Thus it appears that if the protection afforded by vaccination is not perfect, it is superior to any other.” Dr. John Davy, Inspector-General of Army Hospitals,* presents some valuable statistics in relation to the compara- tive mortality of the native population of Malta and the military, among whom smallpox had been introduced by H. M. S. Asia, by which it appears that the mortality among those “not vaccinated” was 1 in 4.7 ; among those “sup- posed to have been vaccinated,” 1 in 23.4 : among those “well vaccinated,” 1 in 15.6 ; and lastly, among those attacked a second time by smallpox, 1 in 10.8. The higher mortality among those supposed to have been vaccinated Dr. Davy explains by the supposition that the majority of the former may have belonged to the infantile age. “As regards the general effect of vaccination in its influence both as affording protection from smallpox-to a considerable extent, and mitigating its severity when not preventing the attack, the facts given are clear and satisfactory. It is a curious circumstance that the proportion of those icho died after a second attack of smallpox teas, as has been already pointed out, greater than in the instances of those icho had the disease after vaccination.'1 The comparative exemption of the British troops serving in Malta is another evidence of the protective influence of vaccination. Dr. Davy says, further, that “the native population (in Malta) in 1830 was estimated at 100,839 persons; amongst whom, it appears, from pre- ceding returns, 1 in every 12.1 was attacked with the disease, and 1 in every 85 died ; but amongst the military, including their wives and children, the proportion attacked was 1 in 188, and the mortality was only 1 in 682.” The petition of Mr. J. F. Marson in support of the “ Vaccination Bill’’T before the British Parliament, in 1856, after declaring that he “has been for upwards of twenty years the resident surgeon of the Smallpox and ATiccination Hospital, in London,” states that the mortality from small- ° Notes and Observations in the Ionian Islands and Malta, &c. Lond. 1841. f Lancet, Aug. 30, 1856. 8 pox in the unvaccinated, of cases taken generally, is thirty- jive per cent., but of children under five years of age, it is Jifty per cent.; and of those who recover, a great many suffer permanent disfigurement, some loss of sight, and others have their health greatly damaged. The mortality, on the contrary, amongst the vaccinated, attacked by smallpox, is seven per cent., taken generally; but among those who may be characterized as the badly vaccinated, it is fifteen per cent. Amongst those, on the other hand, who may be considered to be well vaccinated, that is to say, who have four or more good vaccine cicatrices, the mortality is less than one per cent. In the report of the “Smallpox and Vaccination Com- mittee of the Epidemiological Society’’ of London, presented to the British Parliament in 1853, is collected a mass of evidence abundantly sustaining the protective influence of vaccination. As results are most desirable in a communication like the present, the following statistics collected by the Society are presented : 1st. To prove the influence of vaccination in England: Out of every 1,000 deaths in the half-century from 1750 to 1800, there were of smallpox 96. Out of every 1,000 deaths in the half-century from 1800 to 1850, there were of small- pox 35. 2d. To prove the influence of vaccination on the Conti- nent : In various German States sufficient evidence can be obtained to show that, before vaccination was used, out of every 1,000 deaths there occurred from smallpox 66.5; after vaccination, 7.26. 3d. To prove that in countries where vaccination is most perfectly carried out, smallpox is least mortal : (a.) In this country, (England,) where vaccination is voluntary, and frequently neglected, the deaths from all causes being 1.000, the deaths from smallpox in the fol- lowing towns are as follows: London, 16 ; Birmingham, 16.6; Leeds, 17.5 ; England and Wales, 21.9 ; Paisley, 18; Edinburgh, 19.1; Perth, 25 ; Glasgow, 36; Dublin, 9 25.66; Galway, 35; Limerick, 41 ; Connaught, 60; all Ireland, 49. (6.) In other countries, where vaccination is more or less compulsory, the deaths from smallpox in the following towns are as follows : Westphalia, 6 ; Saxony, 8.33 ; Rhenish provinces, 3.75 ; Pomerania, 5.25 ; Lower Austria, 6 ; Bohemia, 2; Lombardy, 2; Venice, 2.2; Sweden, 2.7; Bavaria, 4. By referring to the accompanying table prepared by Mr. Haile, and found in Mr. J. Simon’s report,* the past and present ravages of the disease may be seen at a glance, and two series of facts be noticed. “1st. How many persons in each million of population died annually of smallpox, before the use of vaccination ; and, 2d. How many persons in each million of population have annually died of small- pox since the use of vaccination.” The author draws the conclusion, as the reader may also do, between the case of Sweden, in the twenty-eight years before vaccination, and forty years soon afterwards : ‘ ‘ During the earlier period, there used to die of smallpox, out of each million of the Swedish population, 2,050 victims annually ; during the later period, out of each million of population, the smallpox deaths have annually averaged 158.” “Or, compare two periods in Westphalia : during the years 1776-’80, the small- pox death-rate was 2,643 ; during the thirty-live years, 1816—’50, it was only 114.” “Or, taking two metropoli- tan cities: you find that, in Copenhagen, for the half-century 1751-1800, the smallpox death-rate was 3,128, but for the next half-century only 286 ; and still better, in Berlin, where for twenty-four years preceding the general use of vaccina- tion, the smallpox death-rate had been 3,422, for forty years subsequently it has been only 176. In other words, the fatality of smallpox, in Copenhagen, is but an eleventh of what it was ; in Sweden, a little over a thirteenth ; in Ber- lin, and in large parts of Austria, but a twentieth ; in West- ° Papers relating to the History and Practice of Vaccination. Presented to both houses of Parliament by command of her Majesty. London, 1857. 10 phalia, but a twenty-fifth. In the last-named instance there now die of smallpox but four persons where formerly there died a hundred.” (P. xxiii.) By reference to the second table, it will be seen that in a number of places observed, the death-rate varies amongst the vaccinated from an inap- preciably small mortality to per cent.; that amongst the unprotected, it ranges from to per cent. These statistics show that the adoption of vaccination has been followed by a reduction of the smallpox mortality to a tenth and a twentieth of its former magnitude. Appiroximate average animal death-rate by smallpox per million oj 1 ivivg popula tion. Terms of years respecting which T particulars are given. err or^‘ Before intro- duction ot vaccination. Jtfter intro- duction of vaccination, 1777—1806, and 1807—1850. Austria, Lower, 2,484 340 1777—1806, and 1807-1850. | ' j-1,421 501 1777—1806, and 1807—1850. Styria, 1,052 446 1777—1806, and 1807—1850. Illyria, 518 244 1777—1806, and 1807—1850. Trieste, 14,046 182 1777—1806, and 1807—1850. Tyrol and Voralberg, 1)11 170 1777—1806, and 1807—1850. Bohemia, 2, 174 215 1777—1806, and 1807—1850. Moravia, 5,402 255 1777—1806, and 1807—1850. Silesia, (Austrian,) 5,812 198 1777—1806, and 1807—1850. Gallicia, 1,194 676 1787—1806, and 1807—1850. Bukownia, 3,527 516 1817—1850. Dalmatia, — 86 1817 —1850. Lombardy, — 87 1817—1850 Venice, — 70 1831—1850. Military Frontier, — 288 1776—1780, and 1810-1850. j P'S„(c!,Trn |3,321 556 1780, and 1810-1850. j j- 2, 272 356 1780, and 1816—1850. Posen, 1,911 743 1776—1780, and 1810—1850. Brandenburgh, 2, 181 181 1776—1780, and 1816 — 1850. Westphalia, 2,643 114 1776—1780, and 1816—1850. Rhenish Provinces, 908 90 1781—1805, and 1810—1850. Berlin, 3,422 176 1776—1780, and 1816—1850. Saxony, (Prussian,) 719 170 1780, and 1810—1850. Pomerania, 1,744 130 1810—1850. Silesia, Prussian, — 310 1774—1801, and 1810—1850. Sweden, 2,050 158 1751—1800, and 1801—1850. Copenhagen, 3, 128 286 11 Death-rate per htcndred cases. Places and times of obser^a- Total No. of cases Among the un- Among the tion. observed. protected. vaccinated. France, 1816—41 .... 16,397 m ‘ 1 Quebec, 1819—20 .... 9 27 If Philadelphia, 1825 .... 240 60 0 Canton Vaud, 1825—29 5,838 24 n Darkehmen, (Durkheim’s) | 1828—29 j 134 CO 0 Verona, 1828—39 .... 909 46f 5§ Milan, 1830—51 .... 10,240 m n Breslau, 1831—33 .... 220 53f n Wirtemberg, 1831}—5} 1,442 2 H 73jI Carniola, 1834—35 .... 441 16} Vienna Hospital, 1834 . 360 51} 12} Carintliia, 1834—35 1,626 1** Adriatic, 1835 1, 102 n Lower Austria, 1835 2,287 25} in Bohemia, 1835—55 15,640 29f Gallicia, 1836 1,059 23} 5} Dalmatia, 1836 723 19| 8} London Smallpox Hospital, j 1836—56 j 9.000 35 7 Vienna Hospital, 1837—56 Kiel, 1852—53 Wirtemberg, no date Malta, no date Epidemiological Society return, ) 6,213 218 6,258 7,570 4,624 30 32 38^ 21. 07 19.7 5 6 3} 4. 2 2.9 no date j In an important paper in the Transactions of the Medical and Chirurgical Society of London (vol. xxxv.,) Dr. J. G. Balfour, Surgeon to Royal Military Hospital, Chelsea, shows that the smallpox mortality of the British navy has not reached a third, nor that of the British army a fourth of the London rate ; and that in the experience of the Royal Mili- tary Asylum for 48 years (within which time 5,774 boys have been received for training,) only four deaths by small- pox occurred, and these all in non-vaccinated boys, who were believed already to have suffered smallpox once before be- coming inmates of the school. “And,” in the words of the reviewer of the above “papers,” “the combined weight of testimony from all sources of evidence is to show that in the 'proportion as vaccination is general and efficient, so is the 12 exclusion of smallpox from the community, and the mortality greatly lessened.”* From a paper on smallpox and vaccination, read before the Boston Sanitary Association by Robert Ware, M. D., and presented to the Senate and House of Representatives of Massachusetts, we learn that in Boston, in 1721, the year in which inoculation was introduced, and when the popula- tion of Boston was only 11,000, there were 5,759 cases of of smallpox, of which 844 were fatal. Thus it appears that over one-half the inhabitants had the disease, and one- thirteenth died of- it. In 1730 there were 4,000 cases and 200 deaths. In 1752, when the population was 15,G84, the number of cases was 5,545 and the deaths 539. Again, in 17G4, there Avere 5,646 cases ; in 1776, 5,292 ; and in 1792, 8,346. If we turn now to the period subsequent to the introduc- tion of vaccination, and take the fifteen years between 1815 and 1830, when vaccination was, in a measure, compulsory and the restrictive system of isolation in force, we find the mortality of smallpox to amount to only fourteen deaths. A still longer period, from 1811 to 1839, shows that only fifty- two deaths from this disease occurred. Not only is it shown by the above statistics that the mortality of smallpox is diminished, but that the frequency of epidemics is also greatly reduced. In the report of the Epidemiological Society of London, prepared by Dr. Seaton, it is shown that “during the ninety-one years (1650-1741) previous to inoculation, there had been 65 distinct and well- marked epidemics, which is a ratio of 71.4 epidemics in one hundred years. During sixty-three years (1741-1803) in which inocula- tion was practiced, and that to a great extent, there were 53 distinct and well-marked epidemics, which is a ratio of 89 epidemics in one hundred years. During the last fifty years, since vaccination has been practised and inoculation declared illegal, there have been ° Brit, and For. Med. Chir. Rev., Oct. 1857. 13 twelve epidemics of smallpox, which is a ratio of 24 epi- demics in one hundred years. Whence it appears that smallpox was epidemic in London before inoculation as 42 ; during inoculation as 54 ; during vaccination as 14 (Ibid., p. 35.) In concluding this branch of the subject, your committee would call your attention to the question addressed, in cir- cular, to members of the medical profession in the United Kingdom, and elsewhere, by Mr. Simon, medical officer to the General Board of Health in London, and to the great unanimity in the affirmative by the eminent authorities to whom it was sent: 11 Have you any doubt that successful vaccination confers on 2arsons subject to its influence, a very large exemption fr om attacks of smallpox, and almost absolute security against death by that disease ?’ ’ Out of 542 persons to whom this question was addressed, including not only the most eminent of British and Conti- nental practitioners, but also foreign governments, through their officials, but two dissenting answers were received ; every other expressed confidence in the practice. 2. Is the protection permanent, or is it modified by any circumstance ? That the protective influence of vaccination is subject to modification, either from the length of time elapsed since the operation or from a greater intensity of the variolous infection overriding the protection during certain periods of life, is very generally believed. Dr. G. B. Wood* says: “It cannot now be denied that a single vaccination does not afford the permanent security it was supposed to do. Probably nearly one-half of those vaccinated successfully are liable to more or less effect from the variolous contagion ; though it is asserted that*when the operation is performed with four or more in- sertions instead of one, the proportion of the protection is ° Practice of Medicine, vol. i. p. 410. 14 much greater.* It is chiefly during the epidemic prevalence of variola that this disposition in vaccinated persons to be affected by the disease is observed. It has very seldom been noticed to any considerable extent at other times. Another interesting fact is, that children of eight years or under are rarely attacked, that from this time to the age of puberty cases begin to be more frequent, and that the greatest number occurs between the ages of fifteen and twenty-five. These two facts it is important to bear in mind. What can be the cause of the inefficiency of protec- tion in certain cases ? It may, the author thinks, be explained by recurrence to the facts stated above, namely, the greater tendency to varioloid during the epidemic prevalence of smallpox than at other times, and greater frequency between the ages of fifteen and twenty-five than at any other period of life. Thus, the security afforded by the vaccine disease, or smallpox, occurring in seasons when no epidemic influence exists, may be effectual under similar circumstances, but may fail during an epidemic when other forces are added to that of the contagious cause. That persons are most liable to the affection between fifteen and twenty-five would seem to show that the changes which take place about the period of puberty, and continue in operation more or less until that of maturity, which may be roughly placed at twenty- five or thirty, are favorable to the development of variolous disease; and that a degree of protection, which might be sufficient either earlier or later in life, is insufficient then.” In the report by Dr. F. W. Sargent of cases attended in the Philadelphia City Hospital in 1845-'G, it is stated that of the cases of varioloid or smallpox after one vaccination, amounting to one hundred and thirty-six, more than twice as many occurred in the ten years from nineteen to twenty- nine, inclusive, as in either of the ten years preceding or following those ages.t In a paper by A. B. Steele, esq., M. R. C. S.,| the follow'- 8 Medico-Chirurgical Transactions, xxxvi. 388. f Am. Journ. Med. Sci. N. 8., xvii. 372. J Liverpool Med. Chir. Journ., July, 1858. 15 ing passage occurs: “The opinion so frequently expressed, that the protection afforded by vaccination in many cases lasts for a certain period only in the life of the individual, is by no means of recent origin, for in 1809, Dr. Brown, of Musselburgh, published the opinion that the protective virtue of cowpox diminished as the time from vaccination increased. Dr. Copland, also, in 1823, arrived at a similar conclusion, from some very remarkable cases which came under his notice, and in the present day there are many authorities of great repute in favor of this view.” Mr. Simon, in the work already quoted, states that in Paris nearly one-third of the whole deaths from smallpox occurred between the age of twenty and thirty, indicating, as he remarks, an appalling amount of post-vaccinal smallpox. He further states that what chiefly attracted attention was that persons who had been vaccinated ten or fifteen years ago, and who during this interval had, perhaps, repeatedly resisted smallpox, would at length, in a certain proportion of their number, yield to the infection. This had most frequently happened during the times when smallpox was severely epidemic among the unvaccinated, and when large masses of persons with vaccination of many years were exposed to the test of a strong epidemic influence. Under this ordeal, it became evident that, for some vaccinated persons the insusceptibility conferred by cowpox was not of life-long duration. And from a careful analysis of cases it was shown that this lessened security of certain vaccinated persons bore at least some proportion to the number of years which, in each case, had elapsed since vaccination, for there were not materials to prove any uniform rate of increase from year to year, and the increase, such as it was, appar- ently continued up to thirty years of age, after which period it seemed that the liability to contract smallpox underwent a continuous decline. Thus, Professor Heim, taking 1,055 cases of modified or unmodified smallpox in vaccinated persons, distinguished them under thirty-five heads, corres- ponding severally to the thirty-five years which had elapsed 16 since vaccination. When this is divided into three successive parts, one for the first tivelve years after vaccination, one for the next seventeen, and one for the following six years, it appears that the average number for each year is, in the first division. 12 ; in the second division, 48 ; in the third, 15. A calculation of similar materials made by Professor Retzius,* with respect to 961 cases in the Stockholm hospital, gave the following series to express the average allotment of smallpox to each year of life in eleven successive quin- quennials, up to the age of fifty-five: 3-}, 41, 13-}, 45}, 51}, 40.20, 17}, 3*. 2}, 1. Mr. Marson’s petition, previously quoted, tends to estab- lish the same result.t “But few patients,” he says, “un- der ten years of age have been received with smallpox after vaccination. After ten years the number began to increase considerably, and the largest admitted are for the decennial period from the age of fifteen to twenty-five ; and although progressively diminishing, they continue rather large up to thirty ; and from thirty to thirty-five, they are nearly the same as from ten to fifteen ; but, as in the unpro- tected, at this period of life the mortality is doubled, show- ing the cause to be probably as much or more depending on age and its concomitants as on other circumstances. In still further advanced life, the rate of mortality will be seen to increase also, as in the unprotected state ; but this ten- dency may be in a considerable degree counteracted, there is but little doubt, by giving more attention than has hitherto generally been given to the perfection of the process of vaccination.” Thus, it appears that age exerts a modifying influence upon the protection of vaccination, by which, during certain years of life, it is lessened. Whether it de- pends upon decadence of that influence, upon original imper- fect vaccination, or upon a greater susceptibility, it needs not now to inquire ; the fact is sufficient for our present purpose. It is not improbable, also, that in addition to the influence of age, a greater susceptibility to the variolous * Gaz. Mfed. de Paris, 1843. t B,ue Book- P- xxx 17 influence may be produced by any marked change in the habits of life of those exposed to it. Recruits and volun- teers may in this manner be more endangered than in the pursuit of their ordinary vocations. From what has been shown thus far, it is probably estab- lished that vaccination, if carefully performed, exerts a positive protecting influence in favor of those receiving it. That in countries where vaccination is general, the fatality of smallpox has under its influence declined to some small fraction of that which formerly prevailed; but that there is at least a doubt as to whether that protection is operative during the period of life when men are most useful, and whether, as they approach adult life, they do not partially or wholly recover that susceptibility to smallpox which vac- cination had once extinguished in them. If a doubt upon this latter point exist in the minds of those to whom the health of our troops is intrusted, surely they have a right to the benefit of that doubt, and it becomes the duty of those in authority to provide the means of safety, and restore or furnish that immunity which the soldier has either lost or failed to receive. 3. Is Re vaccination a preventive of smallpox ? The answer to this question is found in the rich statistical results, mostly from foreign sources, by which so large a reduction both of the mortality and the disease itself is shown as to leave no doubt of its efficacy. Your commit- tee have drawn largely from the reports of revaccination of large masses of men in various military establishments, especially in Germany, collected by Mr. Simon. The earliest experience of this kind came from Wirtemberg. In 1829 the practice of revaccinating the troops of that kingdom was commenced, and its collective results for the next few years are recorded in the following table, show- ing an abstract of these results in relation to five years, terminating with June, 1836. The author calls atten- tion to one great fact deducible from these observations. 18 It is, that ‘ ‘ on the average of more than 14,000 experiments (an immense majority performed at ages between twenty and thirty years,) 34 out of every 100 persons revaccinated developed the same sort of vesicle as would arise from a first insertion of vaccine lymph. And it is important to observe that this renewed susceptibility to cowpox did evidently not depend, so far as could be traced, on any original ineffectiveness of the former vaccination ; for (as is expressly set forth in the second part of the table,) among the 14,384 subjects of vaccination, there were 7,845 who presented strictly normal scars of previous vaccination. Yet nearly a third of this large number gave again exactly such local phenomena as arise in children when vaccinated for the first time. It does not follow from this, however, that every third man would have taken the smallpox if exposed to the contagion ; but that they would have been endangered admits of no doubt.” Total Ratio of success per 3,000 cases vaccinated. Perfect success. Modified success No success. Vaccination of the Wirtem- 1 hers army in the five years > 1831$—’’5$ ' ) 14,384 340. 2 260. 8 411. 5 13,681 of the above mentioned 14,384 military vaccina- tions being classified according to tho marks of previous vaccination or smallpox, the results were as under. Degree of success of re- vaccination. Of cases with nor- mal cicatrices of vaccination there were 7,845, and amoDg these the results per 1,000 were— Of cases with defec- tive cicatrices of vaccination there were 3,545, and among these the results per 1,000 were— Of cases with no cic- atrices of vaccina- tion or smallpox, there were 2,025, and among these the results per 1,000 were— Of cases bearing marks of previous smallpox, there were 266, and among these the results as per 1,000 were— Perfect.... 310.4 280.7 337.3 319. 5 Modified .. 280. 5 259 191. 1 248. 1 None 409. 2 460. 4 471. 6 432. 3 11,565 of the same number being distributed according to age, the results were as follows: 19 Degree of success of re- vaccination. Under 20 years of age, there were revaccinated 124 persons, and the re- sults per 1,000 were— Between 20 and 30, there were re vaccinated 11,157 persons, and the results per 1,000 were— Above 80 years of age, there were revaccinated 2S4 persons, and the re- sults as per 1,000 were— Perfect 338.7 285. 6 426. 1 Modified 322. 6 259. 2 207. 7 None 338. 7 455. 2 366. 2 Inoculation of lymph (whether vaccine or variolous) is, (says Mr. Simon,) so to speak, a finer and more delicate test of susceptibility to the smallpox poison than is the breath- ing of an infected atmosphere ; so that many persons, when the lymph of cowpox or smallpox is inserted in their skin, will give, locally at least, evidences of susceptibility which no atmospheric infection would have elicited from them. And of this perhaps there can be no more ready illustration than the fact that persons who hove marks of previous small- pox were, in at least equal proportion ivith previously vaceinated persons, capable of producing perfect vaccine vesicles; and prob- ably they too, if tested with variolous matter, would have shown at the inoculated part similar signs of susceptibility; whereas, notoriously, of persons wdio have once had small- pox, not nearly one-third becomes afterwards capable of contracting smallpox by frequenting the neighborhood of the sick. For this reason (greatly corroborated by what had already in every-day practice been observed of the immunity of once vaccinated persons,) it was evidently impossible to argue that all who on revaccination yielded perfect vaccine vesicles would, on ordinary exposure to smallpox infection, have been infected with smallpox. Not that all, or nearly all, of them would have suffered, but that from among them more than from among other vaccinated persons the occa- sional sufferers by smallpox would have come. (p. 34.) In the Prussian army, in 1833, there were revaccinated between forty and fifty thousand adults, and in about 33 per cent, of the entire number this revaccination took with perfect success. In a revaccination of Russian soldiers at 20 Kasan, the rate of perfect success was 18* per cent. It was observed at the same time, that in 1,436 persons pre- senting marks of previous smallpox, perfect vaccine vesicles would arise just as often as on persons who had once been vaccinated! “ Of nearly 20,000 revaccinatious practised in the Danish army in the four years 1843- 5 and 1847, more than half were attended with perfect success, and more than a quarter with modified success.’ ’ “Bythe earliest of these various independent observa- tions it was put beyond question that the same lapse of time which renders some vaccinated persons again susceptible of smallpox, renders them also susceptible of cowpox. But it remains to be seen whether that second dose of the latter infection, which it was the object of revaccination to intro- duce, would restore such persons, either permanently or for a long time, to the state of security from which they had declined ; whether by successful revaccination their revived susceptibility to smallpox would be extinguished.” (Ibid.) Now this is precisely the point to which this communi- cation tends, and it seems to be conclusively settled by the experience of the Prussian and Wirtemberg army revacci- nations, which are selected from amongst a humber of others in consequence of their extent and completeness. In proof of the practical value of re vaccination, Mr. Simon states, on the authority of Professor Heim, that in Wirtem- burg— “During the five years, 1833- 7, though smallpox infec- tion had been sixteen times imported into different regi- ments of the army, there had ensued among the 14,384 re- vaccinated soldiers only (in the person of one whose revac- cination two years before had been followed by ‘ modified success’) a single instance of varioloid.” (p. 35.) “In Prussia, just as in Wirtemberg, the practice of re- vaccination grew out of the knowledge that smallpox would ultimately attack a certain proportion of those who had been vaccinated only in infancy. This knowledge, too, had been 21 dearly purchased in the Prussian army ; for during the ten years preceding 1831, cases of post-vaccinal smallpox were increasing in number and fatality ; attacks were counted annually by many hundreds ; and within the three years 1831-’3 there had occurred no fewer than 312 deaths by smallpox. “For the last twenty years the Prussian army has rep- resented an almost entirely revaccinated population : and what has been the contrast? 104 annual deaths by small- pox was the last experience of the former system ; 2 annual deaths by smallpox has been the average for the revaccina- ted army. Analyzing, moreover, the 40 fatal cases of small- pox which the last 20 years have occurred in the Prussian army, we find that only 4 of the number were of persons who (it is said) were successfully revaccinated.” “From 1843 revaccination has been compulsory in the Bavarian army ; and from that date to the present time (1857) neither a single death by smallpox nor even a single case of unmodified smallpox has occurred in that popula- tion.” * “For the last 21 years re vaccination has been general in the Danish army, and for the last 13 years in the Danish navy ; and these two populations have almost entirely escaped contagion during several epidemics of smallpox.” t In Sweden the practice is similar, and the results equally satisfactory. In the Swedish army 1,944 revaccinations were performed in 1852, of which 644, or 33.11 per cent., were successful. In the Baden army revaccination was introduced in 1840, and has since been effected with the greatest punctuality and exactness, with the exception of the years 1848—7 9—7 50, when, in consequence of political events, it lapsed. The number of men attacked in twelve years by variola and varioloid before the introduction of revaccination was 169, whilst the corresponding number after its introduction for * Royal Ministry of War. ■j- Board of Health. 22 a like period was 52 only, of whom only 12 had been operated on with success, the remainder having been revaccinated without result, or else not at all. Dr. T. Graham Balfour, head of the statistical branch of the medical bureau of the British army, in his first general report, presented to Parliament at its last session, has given an interesting statement of the results of the very general vaccination and re vaccination in the Biitish army during the years 1858- 9. We quote the following statements and statistics from Dr. Balfour’s report : “In 1858, in consequence of a number of cases of small- pox having occurred in the army, particularly in India, among persons who had, to all appearance, been previously satisfactorily vaccinated, a departmental order was issued that in future every recruit should, on joining his regiment, be vaccinated, even if he should be found to have marks of smallpox or of previous vaccination, and a monthly return of the results to be forwarded to the director-general. “Under these orders, also, a number of soldiers in whom the marks of vaccination were not deemed satisfactory, were vaccinated, and the results were kept separate from those of the recruits. “As the returns began to be furnished in October, 1858, we have included the results of the last three months of that year with those of 1859, with a view to render avail- able all the information upon this important subject. “The following table shows the degree of success which attended the operation in 1000 cases in each of four different categories, together with the general result upon all the men vaccinated 23 Army, exclusive of Militia. Total No vaccinated. Results. In those who bore marks of previous smallpox. In those who bore good marks of pre- vious vaccination. In those who bore doubtful marks of previous vaccinat’n In those who bore no marks of previous vaccination or smallpox. Total. +-> N 2 . ) f A perfect vaccine 414.50 423.50 294.12 488.96 413.13 X. S3 1 i S L J pustule. j- r j A modified ditto 200.74 179.69 363 44 167.19 201. 23 2