None of the vaccinated patients developed pneumonia, though there were 15 cases among the unvaccinated.
This experiment shows a slight percentage in favor of vaccination, and indicates that there was some decrease in the severity of the secondary infections.
2. The experiment reported by McCoy, Murray and Teeter (17) showed quite opposite results from the above, and was an excellent example of a small though completely controlled test. In an asylum for the insane in San Francisco all of the patients under 41 years of age were divided into two groups—one group was kept as controls and the other was given a vaccine furnished by F. O. Tonney, of the Chicago Health Department. The vaccine contained 500,000,000 each of B. Influenza, Pneumococcus I, II and III, 1,500,000,000 Pneumococcus IV, 1,000,000,000 Streptococcus Hæmolyticus and 500,000,000 Staphylococci. Doses of 0.5 c.c., 1 c.c. and 1½ c.c., which were given at 48–hour intervals. Inoculation was completed on November 15, and the first case of influenza appeared on November 26. The table shows the result.
| Vaccinated. | Not Vaccinated. | |
|---|---|---|
| Persons in group | 390 | 390 |
| Cases of influenza | 119 | 103 |
| Cases of pneumonia | 23 | 17 |
| Number of deaths | 10 | 7 |
3. The report of Minaker and Irvine (18) included several groups of men, the first two of which apparently belonged in our first series. They used a vaccine, each c.c. of which contained 5,000,000,000 B. Pfeiffer, 3,000,000,000 each of Pneumococcus I and II, 1,000,000,000 Pneumococcus III, 100,000,000 Streptococcus Hæmolyticus. In all, they vaccinated 11,179 persons.
(a) Their first group numbered 4,950 persons in quarantine at the Naval Training Station. The quarantine was maintained for 24 days, and no influenza appeared during that time. Three thousand five hundred and fourteen of them were released at a time when there were still 200 to 300 cases of influenza being reported daily in San Francisco. Out of the 3,514 men, 15 had influenza, and there were no deaths.
(b) At the Mare Island Navy Yards 1,950 marines were released immediately after completion of the inoculation. They were turned into Valejo and San Francisco, where influenza was at its height. Only 35 cases, with 1 death, occurred, and these developed shortly after the men were released in San Francisco. This group was controlled with an unvaccinated group of 8,232 persons who remained at Mare Island, and 1,296 cases of influenza, with 65 deaths, occurred among the controls.
(c) At San Pedro 3,100 were vaccinated, and of these 53 had influenza, and there were no deaths. The occurrence among these was compared with the prevalence of the disease in Los Angeles, but this part of the report leaves much to be desired in the way of the relative dates, etc.
(d) The fourth group, consisting of 1,080 civilians, developed 14 cases, with no deaths. However, vaccination of this group was not completed until 21 days after the pandemic had appeared in the community. Minaker’s and Irvine’s analyses show a favorable percentage for vaccination in the first two groups, but their groups three and four were not sufficiently well controlled to be of much help.
4. In a report which appeared during October, 1918, Eyer and Lowe (29) published the results of prophylactic inoculation of 1,000 New Zealand troops with a mixed catarrhal vaccine. They controlled their experiments with 19,000 New Zealand troops who were not inoculated. A comparison of the incidence of acute respiratory disease and influenza during the primary wave of the epidemic as it appeared during June and July, gave two cases among the vaccinated troops and an average of 43.2 cases per thousand among the controls.