Later they reported (58) the results of much larger experiments as carried out at 17 different camps and hospitals. The vaccine which they used was a typical “mixed” vaccine, save that the authors emphasized the advantage of using strains not more than three generations removed from the body. At some of the camps their reports were unfavorable, but upon the whole their results, as summarized below, were most encouraging. In most instances inoculations were completed just prior to the arrival of the autumn epidemic.
Out of a total average strength of 21,759, approximately 16,104 men received full prophylactic vaccination, and approximately 5,700 were uninoculated, or had received only 1 dose; 3,366 cases of influenza developed—15 per cent.; 1.3 per cent. occurred among the vaccinated, while 4.1 per cent. developed in the uninoculated; 8 per cent. of the severe cases among the protected died, as compared to 23 per cent. among the uninoculated. The death rate for all infected cases was 0.26 per cent. among the inoculated and 2.2 per cent. among the uninoculated.
Notanda.—All of the above reports, comprising the “Series I” experiments, indicate that mixed vaccines reduced the number of severe illnesses and lowered the death rate to some extent.
Series II. Those Instances in Which It Is Possible to Compare the Relative Occurrence in Both Vaccinated and Unvaccinated Groups After Vaccination Was Completed
1. The report on prophylactic vaccination at the Hospital for the Insane at Retreat, Pa., was very kindly furnished by Dr. Charles B. Maberry (20). When the epidemic approached, the institution was placed in quarantine and remained free from influenza until October 28, when two cases appeared in nurses who had broken quarantine. Influenza spread in the male ward, but the female wards were kept free during the whole of the epidemic. There were 370 male patients, but 60 were in the infirmary and were not included in the calculation. Out of 310 patients, 210 received vaccines. Ordinary commercial mixed vaccine was used, and vaccination was begun two days after influenza appeared. During the first week there were 40 cases of influenza, 6 of which occurred among those who had received a single dose of the vaccine. After the first week there were 38 cases of influenza, with 10 pneumonias and 5 deaths, among the unvaccinated, giving a morbidity rate of 38 per cent. and a mortality rate of 5 per cent. In the vaccinated group there were no cases after vaccination was completed. Maberry states further that in ward III the only cases which appeared subsequent to vaccination were in six patients who refused preventive inoculations. This appears to be the most favorable of any of the reports.
2. Nurses on duty in hospitals everywhere suffered greatly from influenza, and those of Pittsburgh were no exception. Some of the hospitals vaccinated the nurses during the epidemic and some did not, and it was hoped that by getting a week-by-week comparison of the number of cases among vaccinated and non-vaccinated nurses some reliable data would be obtained. A circular letter sent to all of the hospitals in the community contained a blank asking for the number of nurses, date of appearance of the epidemic, use of vaccine, dates of inoculations, and for a week-by-week occurrence of influenza in each group. Only 7 hospitals complied with the request, and of them only 5 sent complete data. Complete reports were received from the Allegheny General, Columbia, Presbyterian, South Side and St. Francis Hospitals. Of a total of 336 nurses in these 5 institutions, 38 developed influenza in the first week, 48 in the second, 39 in the third, 43 in the fourth, and 45 subsequent to the fourth week, making a total of 213—a morbidity of 63 per cent. The Mercy and St. Margaret’s Hospitals reported the total number of nurses and the occurrence of influenza among them, and adding in their reports there were 521 nurses on duty in 7 hospitals, with 257 cases of influenza, giving a morbidity rate of 50 per cent.; 28 cases of pneumonia and 11 deaths, giving a 2 per cent. mortality rate. The total figures from hospitals where vaccines were used are against vaccination, due partly to the fact that vaccination was started late. In these hospitals the morbidity was 66 per cent. and the death rate 3 per cent. In the hospitals where vaccines were not used the morbidity rate was 20 per cent. and the death rate 1.2 per cent. No dependable data was obtained, but the report from the South Side Hospital was interesting. Of 60 nurses on duty, 36 had influenza and 2 died. Of this number 19 were stricken the first week. Three days after the first cases were admitted to the hospital vaccination was begun, and was given to most of the nurses still on duty. Of those taking vaccines 20 developed influenza and 1 died during the period of immunization, but after the inoculations were completed there were no more cases in either group.
During the epidemic it was said that benefit was derived from the use of vaccines on nurses at the West Penn Hospital, but the writer was unable to obtain a report from this institution. The collected data on nurses was useless, though it is interesting, in that it shows the possibility of making figures prove almost anything you want them to prove.
Series III. Those Instances in Which Vaccination Was Begun After the Epidemic Appeared, and in Which Comparisons of Total Figures Only Are Available
Undoubtedly the largest attempt at prophylaxis against epidemic influenza through the use of “mixed vaccines” was that made under the direction of Dr. W. O. Sherman for the Carnegie Steel and H. C. Frick Coke Companies. The results which Dr. Sherman hoped to attain when he planned using the vaccine and collecting the data have already been given. Commercial mixed vaccines similar to those described under the “Series I” experiment were used, and four doses, three days apart, were given. Inoculations were begun on October 20, 1918, and were completed during the first week of November. Vaccine was administered to the employees and their families without charge. Later cards were given to all employees, and they were made to fill them out and return them. On the cards were blanks calling for the name, age, sex, color, number of inoculations, whether or not the employee himself or any member of his family had had influenza, and how many days the sick individuals had been in bed. Each mill and mine was then supplied with a set of blank forms providing for a complete statistical record of the number of inoculations and the total incidence of influenza, pneumonia and death. From the reports of the respective mills and mines the total figures given in the charts were compiled.
Difficulties were encountered in every part of the work. The vaccine demand was so great that the products of three different firms were used. So many doctors were in service that most of the vaccine had to be given by carefully coached nurses. The bulletins of the United States Bureau of Public Health and of the Allegheny County Medical Society, with their warnings about influenza vaccines being only in the experimental stage, appeared just at the time the work was begun and caused a great many to refuse to complete vaccination after one or two doses had been given. So few medical men were left that it was impossible to have them see all cases and so determine the nature of many of the illnesses which were occurring. It was assumed, therefore, that any employee who had fever and was sick for a period of three days had influenza, and that any who were confined to bed for seven days or more had pneumonia. The figures of the central offices were made up from the reports of 14 steel mills, 1 cement factory, 4 warehouses and 57 mining districts. The accuracy of data depended on the careful work of a great many local statistical workers, which made individual variations hard to control. The greatest difficulty of all, however, lay in finding a common basis for comparisons of the incidence of influenza, pneumonia and death in the vaccinated and non-vaccinated groups, since the data on the former group included the occurrence only after the peak of the epidemic had been passed, and that of the latter group included the occurrence for the entire epidemic.