August 1st, 2018
Recently obtained military documents reveal that during the 1960s the Department of Defense knew of an ongoing problem with jet gun injectors and attempted to remedy the issue. These documents reveal that the military believed if the manufacturer conducted a performance test on every jet injector any defective devices would be removed and jet injections would be safe. However, as this article will demonstrate, jet injectors were not safe, the performance test conducted was inadequate, and an undesirable phenomenon called fluid suck-back was not a defect but a common occurrence within all devices.
In 1967 the Department of Defense (DoD) created a military specification for the most widely used jet gun injector in the U.S. military. The specification came six-years after jet injectors were standardized throughout the Armed Forces (Army, 1961) and thirteen-years after the first prototype was used upon military personnel (Star-Democrat, 1954; Warren et al., 1955).
A military specification, as defined by the Government Accountability Office, is a document describing “the physical and/or operational characteristics of a product.” Military specifications generally state the DoD’s requirements, dimensions, standards, and objective(s) of a product. The specification then serves as a contract between a manufacturer and the DoD on the degree of quality with which the product is to be built.
Here the specification serves as evidence on what the DoD knew about jet injectors and how they perceived to overcome defects within these devices. The contents within this first jet injector specification from 1967 disclosed two startling bits of information: (1) Jet injectors posed a threat of sucking any fluid on the nozzle orifice back into the gun, and (2) jet injectors induced bleeding.
Specification Acknowledged Fluid Suck-Back
“On cocking the gun, there shall be no drawback of fluid at the jet nozzle,” states the 1967 specification document for the Automatic Jet Hypodermic Injection Apparatus (DoD, 1967). The 1975 specification document for the non-electric version known as the Ped-O-Jet reads verbatim (DoD, 1975).
These documents were referring to the undesirable phenomenon known as fluid suck-back, in which any fluid or blood resting on the nozzle is sucked back into the orifice of the jet injector and contaminates the next dosage to be fired.
The 1967 specification reveals the DoD viewed fluid suck-back as a defect and assumed conducting a performance test on every jet injector would isolate and remove faulty devices. Although this strategy was only the latest approach at trying to remedy a longstanding problem.
Fluid Suck-Back: A Longstanding Problem for the DoD
As we have written elsewhere:
During the mid- to late-1950s, researchers within the Department of Defense (DoD) became cognizant of the undesirable phenomenon of fluid suck-back. The observation prompted researchers at Walter Reed Army Institute of Research along with engineers at the Medical Equipment Development Laboratory at Fort Totten (MEDL) with the task of remedying the problem. By 1959, the DoD developed a new multi-use nozzle jet injector (MUNJI) that was intended to be an improvement over previous models. The device was called the Automatic Jet Hypodermic Injection Apparatus, or more commonly known as the Ped-O-Jet.
Lt. Colonel Abram Benenson, who oversaw the use of jet injectors within the DoD, acknowledged the collaborative work that birthed the Ped-O-Jet in a 1959 paper:
“[S]ince July 1957, we [Benenson and Lt. Col. Robert Lindberg] have been responsible for the development of jet injectors for immunization. Our field and laboratory studies depended on the efforts and support of Captain Adrain D. Mandel and Mr Charles E. Buckler; engineering support was furnished by the Medical Equipment Development Laboratory, Fort Totten, New York, where the basic principle was improved into the current multidose jet injector” (emphasis added) (Benenson, 1959).
Aaron Ismach, the inventor of the Ped-O-Jet and a civilian engineer at MEDL, reported that previous multi-use nozzle jet injectors of the 1950s allowed for fluid suck-back. In his December 14th, 1959 patent, Ismach stated, “unlike most earlier hypodermic jet injection guns, the instant invention is free from sucking fluid back from a patient either during or after the firing cycle is completed so that the danger of cross-infection is almost completely avoided” (Ismach, 1962). The Press-O-Jet would be one of the “earlier hypodermic jet injection guns” that Ismach was referencing.
Ismach’s patent specifically acknowledged the potential of fluid suck-back occurring when cocking the gun but states a ball check valve, located within the nozzle head, prevents this from happening. “The ball check valve 44 serves to prevent the entry of any air or suckback of any fluid during the loading cycle of the vaccine pump…” (Ismach, 1962).
From Ismach’s assertion the issue of fluid suck-back clearly rests upon the efficacy of the ball check valve. To gain an understanding of how Ismach improved upon the ball check valve, Jet Infectors compared the patents of the Press-O-Jet and Ped-O-Jet. One noticeable difference stood out—the ball check valve on the Ped-O-Jet was spring-loaded to help keep it shut. The Press-O-Jet did not contain a spring.
However, if the spring-loaded ball check valve had resolved the issue of fluid suck-back, as Ismach proclaimed, it would not have received mentioning within this specification. Said differently, if the problem was remedied it would not have been brought-up eight-years after Ismach claimed to have fixed the issue in his patent. Therefore, it can be said with confidence that the DoD was still observing fluid suck-back within the Automatic Jet Hypodermic Injection Apparatus (Ped-O-Jet).
Critics may claim, if every device had to pass a performance test then the faulty devices would have been removed from stock. Although this depends on the quality with which the performance test was conducted and is based upon the assumption that fluid suck-back indicated that the device was defective. Was the performance test valid and thorough? Was fluid suck-back evidence of a defect within a particular device?
Performance Test was Inadequate
The performance test outlined within the specification was inadequate for several reasons. First, the premise of this test was completely faulty. Within the sentence “upon cocking the gun, there shall be no drawback of fluid at the jet nozzle,” is the subtle revelation by DoD that fluid was present on the surface of the nozzle. The presence of fluid on the nozzle orifice after an injection posed no threat in a performance test but during actual use could serve as a mode of cross-contamination when the nozzle is pressed against the arms of multiple patients. Any vaccine or blood resting upon the nozzle orifice would be cross-contaminated to a subsequent person. Therefore, any fluid on the exterior nozzle after an injection should have been recognized as contamination.
Second, the performance test only evaluated fluid suck-back based upon a limited set of parameters, which were outlined within the military specification. For instance, the specification stated:
- “The injection apparatus shall be mounted in a test jig designed to fire the apparatus at the rate of 1200 shots per hour” (DoD, 1967). Therefore the device was stationary, held vertically, and fired at a rate of once every three seconds.
- “The unit under test shall fire at least 250 1 cc shots and 500 1/2 cc shots of water continuously without failure at the rate of 1200 shots per hour” (DoD, 1967).
- “On cocking the gun, there shall be no drawback of fluid at the jet nozzle” (DoD, 1967). To pass the test, every time the gun was cocked, the device could not suck any fluid on the nozzle orifice back into the device.
This test failed to assess if fluid suck-back occurred under other circumstances. For instance, was fluid suck-back observed when the gun was cocked in a horizontal position, as opposed to just the vertical position as mentioned in the performance test? Or what about the human factor? Did fluid suck-back occur when the gun was being moved up and down and back and forth by the operator during real-life conditions, as opposed to just being tested in a stationary jig? For these reasons, the performance test was inadequate as it failed to assess the jet injector under real-life conditions.
Subsequent research conducted outside of the military did evaluate the above questions. In 1977 researchers within the CDC’s Hepatitis Laboratories Division in Phoenix, Arizona, independently—and secretively—assessed the safety of Ped-O-Jet injectors. In their observations, a drop of fluid was observed on the nozzle orifice after firing an injection. “The drop would disappear (back into the injection nozzle head) in 3 to 5 seconds if the gun was held vertically or the drop would disappear immediately if the gun was cocked in a horizontal position” (CDC, 1977). These investigations represented real-life use of the Ped-O-Jet and did not use any jig.
The CDC concluded that “disappearance of the fluid drop are common during clinical use of the jet injector” (CDC, 1977). Therefore fluid suck-back was not evidence of a defective device but of an inherent problem with jet injectors in general.
Although the wise critic may retort that the stipulation “every time the gun was cocked it could not suck any fluid back” is pretty comprehensive. Yet this is a faulty conclusion. This is not a question of if contamination occurred but how. For instance, if the gun was cocked while held horizontally, fluid suck-back occurred immediately. Or without even cocking the gun, fluid suck-back was found to occur in 3 to 5 seconds if the gun was held vertically. If the gun was fired within 3 seconds, fluid suck-back may not have occurred but there was still contamination on the nozzle orifice. Regardless of whether contamination was on the external nozzle orifice or within the internal fluid pathway, the jet injector was unsterile.
Second, arguing whether fluid suck-back occurs when held vertically or horizontally or within or beyond three seconds is ultimately pointless when subsequent research has identified contamination occurring during the jet injection process. Whereas fluid suck-back occurs in between injections, an undesirable phenomenon called Retrograde Flow occurs during the injection.
As we have stated in our section, Faulty Design Created Inherent Risks, near the end of jet injection process, the pressure of the jet stream impinging the skin would be less than the pressure of the fluid deposited within the newly constructed hole in the vaccinee’s arm. Since the jet stream was too weak to further deepen the hole, it moved backwards and flowed out of the hole and back into the jet injector. This would be an expected phenomenon in almost every jet injection due to the continuous depletion of pressure.
Still critics may say, this was a performance test, not a clinical test. What did the clinical test find?
Glad you asked.
The military specification required clinical testing of the jet injector to be conducted to ensure its safety. The specification stated,
Clinical Tests. The government will arrange for the clinical testing of the hypodermic injection apparatus on patients using one of the preproduction samples in order to insure the proper functioning of the sample, including injecting with a minimum of whealing or bleeding and other characteristics described herein (emphasis added) (DoD, 1967).
Somewhere unbeknownst to us there exists a military document or study that conducted a clinical test on patients to uphold the safety of the Automatic Jet Hypodermic Injection Apparatus, as described above. It is unclear if this document still exists or where it might be located. It also is unclear if the “government,” that is the Defense Personnel Support Center, conducted this assessment, if it was outsourced, or if prior studies conducted by the DoD, Centers for Disease Control or World Health Organization were deemed acceptable.
Despite whatever the clinical test stated, we know with certainty the device was not safe. At the time, blood detection was very primitive and the clinical test would not have been capable of identifying low, yet infectious levels of blood. For this reason, the results of the clinical test would have been underreported or have given false negatives. For instance, if a 1959 safety test conducted by Walter Reed Army Institute of Research was used as the clinical test then the results would have been underreported. Moreover, blood-borne pathogens such as Hepatitis C and HIV were unknown in 1967. Without a means of testing viruses not yet known to the human race transmission would have gone undetected.
In our analysis of the this military specification, we have already acknowledged numerous safety hazards, such as: the presence of contamination on the outside of the jet nozzle; the ball check valve did not prevent fluid-suck back from occurring; the performance test, which was to remove defective devices, was inadequate and did not evaluate real life conditions; subsequent research found the internal components of the jet injector became contaminated due to a process called retrograde flow, and now we read that the specification acknowledged the presence of blood during the jet injections.
Specification Acknowledged Jet Injectors Induced Bleeding
“The government will arrange for the clinical testing…in order to insure the proper functioning of the sample, including injecting with a minimum of whealing or bleeding” (emphasis added) (DoD, 1967).
Here the military openly acknowledged bleeding during the vaccination campaign. Yet most shockingly, the DoD did not state there shall be no bleeding during usage but a “minimum of…bleeding.” The DoD’s 1970 specification for the intradermal nozzle attachment recognized bleeding as a distinctive attribute of the injection: “The injection shall produce a pronounced wheal and shall be characterized by a minimum of bleeding and skin trauma” (emphasis added) (DoD, 1970). Clearly the DoD found minimal bleeding to be acceptable with jet injection but failed to quantify what constituted as a “minimum” of bleeding within any of the specifications.
The presence of any blood should have warranted safety precautions to be implemented by the DoD. Indeed knowledge on blood-borne pathogens was limited in 1967. However, the risk of contracting hepatitis from blood was known of during this time. “It is possible for a patient to be a carrier of hepatitis and capable of seriously infecting another patient with the disease, although the carrier himself may show none of the symptoms associated with hepatitis,” wrote Ismach in his 1959 patent for the Automatic Jet Hypodermic Injection Apparatus (Ismach, 1962). Despite acknowledging the danger of hepatitis, Ismach minimized the risk of such transmission via jet injection.
Yet the Eli Lilly & Company appropriately recognized the risk of transmitting hepatitis via jet injectors. In 1962, five years before publication of the first jet injector specification, the company issued a warning on the product insert of its influenza vaccine, which stated: “If the nozzle becomes contaminated with blood or serum, it should be replaced or resterilized before further use to prevent the transmission of serum hepatitis virus or other infectious agents from one person to another” (Eli Lilly & Co., 1962).
Nowhere within any specification did the DoD caution against the risk of transmitting hepatitis when the jet injector became contaminated with blood. Why the DoD failed to implement the same level of safety precautions as a pharmaceutical company will be a question forever unanswered.
In the Years Following…
In the years following this first jet injector specification, several amendments and notices were issued, as noted below:
Here is the original 1967 military specification for the Automatic Jet Hypodermic Injection Apparatus.
Amendment 1, issued on October 31st of 1972, cannot be found. Whatever alterations were made are unknown.
Amendment 2, issued in 1974, made several alterations. The most critical of the changes was suspending the clinical test requirement. No longer was the Automatic Jet Hypodermic Injection Apparatus mandated to undergo clinical testing but only subjugated to testing “if deemed necessary” (DoD, 1974).
In 1978, the DoD had published a military specification for the creation of an Automatic Jet Hypodermic Injection Apparatus training device. The device could be used to train military personnel in administering antidote for nerve agents without the actual antidote attached (DoD, 1978). A working jet injector would not suffice for training purposes because if the jet injector is dry-fired, meaning it is fired without any liquid medicament, the device would become damaged.
It is noteworthy to include, in light of the CDC implicating a multi-use nozzle jet injector in the transmission of Hepatitis B at a weight reduction clinic in 1985, the DoD should have requested another clinical test on the Automatic Jet Hypodermic Injection Apparatus to be conducted. However, no documents have ever surfaced indicating any such follow-up testing was ever performed.
In 1988, the specification underwent a process called validation, in which the specification was reviewed to determine if the document was current and accurate. Notice 1 stated in its entirety, “Military Specification MIL-H-36505, dated 12 June 1967, has been reviewed and determined to be current” (DoD, 1988). However, the documented failed to describe the processes involved. Also, there was no mentioning of any updated clinical testing to ensure the safety of the technology during the validation process.
In 1994, the DoD issued Notice 2 which stated in its entirety, “Military Specifications MIL-H-36505, dated 12 June 1967 and MIL-H-36505 (2), dated 19 July 1974 is hereby cancelled without replacement” (DoD, 1994). During the 1990s, the DoD had noticed the vast amount of military standards created unnecessary restrictions as well as increased costs. Following Secretary of Defense William Perry’s memorandum in 1994, the DoD rescinded a lot of specifications opting instead for the use of industry standards. Despite the cancellation of this specification, the DoD still used the Automatic Jet Hypodermic Injection Apparatus until December 5th of 1997 when the device was pulled due to safety concerns.
Jet Infectors review of the Department of Defense’s military specification for the most widely used jet injector within the U.S. military demonstrates that changes to the ball check valve in 1959 were insufficient in alleviating the risk of cross-infection and that the military was still attempting to remedy the issue of fluid suck-back in 1967.
The performance test, which attempted to remedy the issue, only assessed for fluid suck-back on a limited set of parameters and failed to assess real life conditions. The DoD failed to see that fluid suck-back was not a defect but an inherent problem and thus frequently occurred. The DoD also failed to identify any fluid on the outside of the nozzle as contamination. For these reasons the specification was inadequate.
Subsequent research has shed light on another inherent fault of jet injector technology. In administering the jet injection an undesirable phenomenon called retrograde flow allowed for blood and bodily juices to flow back into the internal components of the gun during the injection. This was a cataclysmic breach of sterility.
Furthermore, the clinical test would not be capable of identifying the transference of low but infectious volumes of blood and could not test for blood-borne pathogens, such as Hepatitis C, which would not be identified until 22-years later.
On two occasions the DoD failed to retest the safety of jet injectors: Once after a hepatitis outbreak implicated a multi-use nozzle jet injector in 1985 and again during the validation of this specification in 1988. The DoD should have requested updated clinical tests to be performed to ensure the safety of those vaccinated.
It is indisputable, the DoD, the largest consumer of jet injectors, repeatedly failed to appropriately assess the safety of these devices.
- (Army, 1961) Department of the Army. Annual Report of the Surgeon General United States Army Fiscal Year 1961.
- (Benenson, 1959) 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].
- (CDC, 1977) CDC. DHEW Memorandum: Informal Quarterly Report of October-December 1977. From: Special Investigations Section (Petersen NJ, Bond WW, Carson LA) to: Deputy Director (Favero MS), Hepatitis Laboratories Division, Phoenix, AZ (unpublished).
- (DoD, 1967) Department of Defense. Military specification: hypodermic injection apparatus, jet, automatic. Defense Supply Center, Phil-Troop Support / Medical Items of Supply. MIL-H-36505, 12 June 1967. Accessible here.
- (DoD, 1970) Department of Defense. Military specification: nozzle, automatic, jet hypodermic injection apparatus. Defense Supply Center, Phil-Troop Support/ Medical Items of Supply. MIL-N-36667, 19 March 1970. Accessible here.
- (DoD, 1974) Department of Defense. Military specification: hypodermic injection apparatus, jet, automatic. Defense Supply Center, Phil-Troop Support / Medical Items of Supply. MIL-H-36505 (2), 19 July 1974. Accessible here.
- (DoD, 1975) Department of Defense. Military specification: hypodermic injection apparatus, jet, foot operated. Defense Supply Center, Phil-Troop Support / Medical Items of Supply. MIL-H-37084, 11 June 1975. Accessible here.
- (DoD, 1978) Department of Defense. Military specification: hypodermic auto-injector, demonstration. Defense Supply Center, Phil-Troop Support / Medical Items of Supply. MIL-T-37923, 31 October 1978. Accessible here.
- (DoD, 1988) Department of Defense. Military specification: hypodermic injection apparatus, jet, automatic. Defense Supply Center, Phil-Troop Support / Medical Items of Supply. MIL-H-36505 (2), Notice 1, 22 August 1988. Accessible here.
- (DoD, 1994) Department of Defense. Military specification: hypodermic injection apparatus, jet, automatic. Defense Supply Center, Phil-Troop Support / Medical Items of Supply. MIL-H-36505 (2), Notice 2, 31 August 1994. Accessible here.
- (Eli Lilly & Co., 1962) Eli Lilly and Company. Influenza Virus Vaccine Polyvalent (Types A and B) [vaccine product insert; 03516, 80:12, PA 1787 AMP]. Indianapolis, IN: Eli Lilly and Company; December 28, 1962;102.
- (Ismach, 1962) Ismach, Aaron. “Multi-dose jet injection device.” United States Patent 3,057,349. 9 October 1962.
- (Star-Democrat, 1954) Star-Democrat. Painless Shot. 28th May 1954. pg. 35.
- (Warren et al., 1955) Warren J, Ziherl FA, Kish AW, Ziherl LA. Large scale administration of vaccines by means of an automatic jet injection syringe. JAMA 157:633–637, 1955.
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