Letter from Richard G. Hodges, United States Army Air Forces to Michael Heidelberger
During World War II Heidelberger served as a member of the Pneumonia Commission established by the Board for the Investigation
and Control of Influenza and Other Infectious Diseases (later the Army Epidemiological Board) under the Surgeon General of
the U.S. Army. The Commission, headed by Colin MacLeod, a microbiologist and co-discoverer of the genetic properties of DNA,
organized a trial of a vaccine against pneumococcal pneumonia developed by Heidelberger. The trial, carried out among 20,000
trainees at an air base in Sioux Falls, South Dakota, proved that a vaccine made from a mixture of purified capsular polysaccharides
from four different types of pneumococcus (types I, II, V, and VII) provided effective protection against pneumonia when compared
with a control group which received saline solution, and which had a higher incidence of the disease. As Hodges, who oversaw
the study on site, reported in this letter, not a single soldier who had been immunized had contracted the disease, compared
with ten who had been given saline solution.
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1945-01-02 (January 2, 1945)
Hodges, Richard G.
[United States Army Air Forces]
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Medical Subject Headings (MeSH):
Antigens and Antibodies: Heidelberger and The Rise of Quantitative Immunochemistry, 1928-1954
[Lab notes from a vaccine trial at Sioux Falls Army Air Field] [1944-1945]
Letter from Richard G. Hodges, United States Army Air Forces to Michael Heidelberger (November 3, 1944)
Letter from Michael Heidelberger to Richard G. Hodges, United States Army Air Forces (January 18, 1945)
Inclosed are two lists of bloods that we have taken. The shorter list covers the first bloods which we sent to you about two
weeks ago. The second list is composed of repeat bloods which we took last week. There will be one more batch of about fifteen
(15) bloods, which we plan to take this week. As you can see there is considerable irregularity in the intervals between
the first and second bloods. This was unavoidable due to administrative difficulties. I trust that it will not make too much
difference in your results.
In regard to the names which you questioned: 13, 190 and 312 is "Lamprinakos"; 888 is "Dennis, W.".
There are several men on who we got first bloods but whom we could not find for a second bleeding since they had left the
field. This, of course, represents the margin of error which we took into consideration when we planned this phase of the
experiment. As a matter of fact I am somewhat surprised that we obtained as many repeat bloods as we did.
Pneumonia is still unfrequent on the Post but as I pointed out in my last letter we already have enough cases to give our
results good statistical significance. The score at present stands: saline group, 10; permanent party, 6; ride group; means
that there is only one chance in well over ten thousand that the apparent benefit of the injections is due to the turn of
Indications are that we shall be able to continue the study for at least two months more. I would suspect that toward the
end of January we shall begin to see another increase in the instance of pneumonia.
With very best regards to you, to Miss Pauli and to my other friends at PH.