2. Number of employees who did not have influenza 3,986
——————
Total number of employees 5,261
3. Total number of persons
inoculated No inoculations 3,091
One inoculation 232
Two inoculations 249
Three inoculations 479
Four inoculations 1,210
——————
Total 2,170
4. Cases influenza developed
after No inoculations 705 55%
One inoculation 111 48%
Two inoculations 91 36%
Three inoculations 129 27%
Four inoculations 239 19%
——————
Total 1,275
5. Cases influenza pneumonia 40%
developed after No inoculations 283 of (4
One inoculation 75 67%
Two inoculations 59 64%
Three inoculations 51 42%
Four inoculations 69 28%
——————
Total 537
6. Deaths from influenza and “flu 5.6%
Pneumonia” after No inoculations 40 of (4
One inoculation 5 4.5%
Two inoculations 0
Three inoculations 0
Four inoculations 3 4.3%
——————
Total 48
Charts I and III show a decrease in the incidence of influenza in direct
proportion to the number of inoculations given. This finding would have
been very important had vaccination been completed before the epidemic
appeared. There is, however, no convincing evidence in either of these
charts that the vaccine cut down the relative number of pneumonias, or
decreased the death rate to any appreciable extent. Chart I also shows
the interesting fact that influenza occurred slightly more often among
those who had one inoculation than among those who were not vaccinated
at all.
Chart II would indicate that influenza occurred much less frequently in
the vaccinated than in the control group, but a closer analysis brings
out the contradictory finding that influenza occurred at the same rate
in the group of 634 persons who had only 1 dose that it did in the group
of 1,271 who completed the course.
The reports from the separate communities were so conflicting that to
attempt to analyze them leads only to confusion.
No reports of harmful effects from the use of the vaccine were received,
and several physicians who attended sick employees say that, even though
the figures do not show it, they feel certain that the vaccinated
persons in general were not as sick as those who were not vaccinated.
On account of the conditions under which the vaccinations were done and
the reports compiled, Dr. Sherman has not felt justified in making a
report, fearing that erroneous conclusions might be drawn from the data.
We are greatly indebted to him for the use of his reports, without which
our account of the influenza epidemic in Pittsburgh would have been very
incomplete.
2. Another large steel corporation who used vaccine but asked that their
names be withheld furnished the following report. During the epidemic
the company offered free vaccination to its 27,000 employees and their
families. Commercial mixed vaccines were used, three injections given,
and vaccination begun on October 19, which was about the time of the
peak of the epidemic in Pittsburgh. The results include a record of all
employees who lost over six days between October 1 and November 30.
───────────────────────────────┬────────────┬───────────┬───────────
EMPLOYEES │ MORBIDITY │ PNEUMONIA │ MORTALITY
───────────────────────────────┼──────┬─────┼─────┬─────┼─────┬─────
│ No. │ % │ No. │ % │ No. │ %
───────────────────────────────┼──────┼─────┼─────┼─────┼─────┼─────
Received only one dose 3,895│ 511│13.13│ 31│ 0.8│ 28│ 0.72
Received only two doses 3,329│ 414│12.44│ 40│ 1.2│ 19│ 0.57
Received all three doses 9,897│ 468│ 4.75│ 46│ 0.46│ 32│ 0.32
───────────────────────────────┼──────┼─────┼─────┼─────┼─────┼─────
Total of above 17,119│ 1393│ 8.14│ 117│ 0.68│ 79│ 0.46
Received no doses 10,036│ 1522│15.17│ 154│ 1.53│ 106│ 1.06
───────────────────────────────┼──────┼─────┼─────┼─────┼─────┼─────
Total for both groups 27,155│ 2915│11.66│ 271│ 1.10│ 185│ 0.76
───────────────────────────────┴──────┴─────┴─────┴─────┴─────┴─────
Before satisfactory conclusions can be drawn from these figures it is
necessary to know how many of the 10,036 persons became sick before
vaccination, and whether or not the rate of decrease in this group was
not similar to that shown by the number of patients who developed
influenza during the intervals between their doses of vaccine. The
relatively high percentage of cases following the first and second doses
are capable of explanation on one, or perhaps on all, of the three
following grounds: (a) the general subsidence of the epidemic, which
showed a rapid decrease by the time the third dose was given; (b) the
increased protection afforded by the three doses of vaccine, and (c) the
broken resistance of the patient following sudden sensitization by the
vaccine.
3. Rosenow (21) prepared a mixed vaccine by growing the various bacteria
in glucose broth, for from 18 hours to 36 hours, centrifuging and
suspending the sediment in salt solution and making up the vaccine on a
percentage basis.