Army’s 1959 Introduction of the Ped-O-Jet Injector

Jet Injectors = Jet Infectors

March 6, 2016

military jet injector vaccinations

In the late 1950s, Aaron Ismach and Abram Benenson developed a jet injection device, originally known as the Multidose Jet Injection Device. This device became more commonly known as the Ped-O-Jet due to later development of a non-electrical foot-pump model. At the time, Mr. Ismach was a civilian scientist working for the US Army Medical Equipment and Research Development Laboratory at Fort Totten, New York and Dr. Benenson was a Colonel in the US Army Medical Corps.

Ismach and Benenson’s device was capable of inoculating 1,000 persons an hour. A novel invention for it’s time. The device allowed for rapid and expedient immunization of a large population. In a military setting, the device allowed for the mass immunization of recruits in bootcamps, training facilities and depots.

Multidose Jet Injection Device

Benenson reported on the introduction of this device in his 1959 article Mass Immunization By Jet Injection.

1959 Benenson- Mass immunization by jet injection-1

(photo by Benenson, 1959)

In the article Benenson reported:

There have been no reactions suggesting intravenous infection in over 100,000 injections despite occasional bleeding indicating that the jet had traversed a blood vessel; this may well be explained by the fact that when one milliliter of material is diffused through the tissues, only insignificantly small amounts could possibly enter a vessel. Obviously one should not inject over a major vessel (emphasis added).

Benenson later wrote, “bleeding from the point of entry has been noted in 5 to 10% of recipients.” His initial investigations found,

when it [bleeding] does occur, the blood continues to ooze staining the shirt, perhaps because infiltration of vaccine into the tissue interferes with normal clotting mechanism. This bleeding is simply controlled by applying pressure for a short period of time with a pledget of absorbent cotton. Increased bleeding and immediate wheal formation are found with incorrect orifice design. When the injector is not held firmly so that the tip moves while vaccine is being discharged, the skin can be cut; this is minimized by proper technique, a dry skin and a roughened surface on the jet nozzle.

Moreover, Benenson reported,

The problem of hepatitis has been minimized. After each of the five different injection sessions, with no cleansing of the nozzle between a total of 762 recipients, the nozzle was soaked in saline and then precipitin tests were set up with rabbit and horse antihuman serum. The results were negative, indicating the presence of less than 15 gammas of human serum, if any (emphasis added).

For those of us who do not know, a gamma is an out-dated term for a unit of measurement. François Cardarelli (2003) explains in the Encyclopedia of Scientific Units, a gamma is a unit of measure of mass equal to one microgram (1µg).

Benenson reported, “the presence of less than 15 gammas of human serum” on the nozzle of the Ped-O-Jet style-like injector after administering 762 injections. 15 gammas of human serum equates to 15 micrograms.

To put this into perspective based upon advances in modern science, in 1984 Feinman and colleagues reported the minimum volume of blood capable of transmitting the hepatitis B virus to be 10 picoliters (Feinman et al., 1984).

In a 2013 interview, Dr. Peter Hoffman, an epidemiologist at the United Kingdom’s Health Protection Agency, estimated the minimum volume of blood capable of transmitting the hepatitis C virus is estimated to be 100 picoliters (Hoffman, 2013).

In doing the math, 15 micrograms converts to 0.015 microliters, or rather 15,000 picoliters. Therefore, this 15 gammas of human serum is capable of holding 1,500 hepatitis B virions and 150 hepatitis C virions.

So the question arises: If 5 to 10 percent of recipients bleed, how much blood was present within the internal components and upon the nozzle between each injection? After administering 762 injections the nozzle was soaked in saline as a prerequisite for conducting a precipitin test. Although, based upon the saline mixture used, did any of the blood dissolve in the salt solution (saline)? Essentially how reliable was the test conducted?

Weniger, Jones, and Chen (2008) reported of Benenson’s study stating that the, “military [was] unable to detect surrogates for viral agents in assays available in that era.”

Herein, the most widely used jet injector within the United States military was noted for “occasional bleeding,” whereupon the “the problem of hepatitis” could only be “minimized” and not eliminated. Interesting wordage—problem of hepatitis. Not “risk” of hepatitis. Problem.

Although this study reported no cross-contamination, the study was blind to the later advancements science procured. HCV was discovered in 1989. The transmissibility rate of HBV was discovered in 1984. The unit of measurement known as a picoliter, which is roughly a million times smaller than a period on this page, was recognized in 1960.

Upon further review, it could have been possible for hepatitis virions to have been transmitted in the amount of blood reported during the administration of the Multidose Jet Injector in Benenson’s 1959 report.


  • Benenson AS. Mass immunization by jet injection. In: Proceedings of the International Symposium of Immunology, Opatija, Yugoslavia, 28 September—1 October 1959 (International Committee for Microbiological Standardization, Secton of the International Association of Microbiological Societies). Zagreb: Tiskara Izdavackog zavoda Jugoslavenske akademije; 1959;393–399 [Library of Congress QW 504 I60p 1959].
  • Feinman SV, et al. DNA: DNA hybridization method for the diagnosis of hepatitis B infection. J Virol Methods 1984;8(3):199-206.
  • François Cardarelli (2003). Encyclopedia of Scientific Units, Weights and Measures. Springer-Verlag London Ltd. ISBN 978-1-4471-1122-1.
  • Hoffman, PN. Personal communication. February 28, 2013.
  • Weniger BC, Jones TS, & Chen RT. The Unintended Consequences of Vaccine Delivery Devices Used to Eradicate Smallpox: Lessons for Evaluating Future Vaccination Methods. 2008.

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