Impact of CDC’s 1993-94 Unpublished Study – Part I

CDC’s third evaluation into multi-use nozzle jet injectors created a cataclysmic change within the agency. No longer were jet injectors viewed as risk-free. The benefits these devices previously provided within mass immunization campaigns were now being thwarted by a growing fear of transmitting infectious viruses.

As a direct result of the investigation by Grabowsky and colleagues, CDC immediately issued a new, heightened warning on the risks of using multi-use nozzle jet injectors. The warning within the MMWR General Recommendations on Immunization, dated the 28th of January 1994 preceded Grabowsky filing his unpublished draft with CDC in April of 1994. The CDC warning stated,

The multiple-use nozzle jet injector most widely used in the United States (Ped- O-Jet) has never been implicated in transmission of bloodborne diseases. However…laboratory studies in which blood contamination of jet injectors has been simulated have caused concern that the use of multiple-use nozzle jet injectors may pose a potential hazard of bloodborne-disease transmission to vaccine recipients. This potential risk for disease transmission would exist if the jet injector nozzle became contaminated with blood during an injection and was not properly cleaned and disinfected before subsequent injections. The potential risk of bloodborne-disease transmission would be greater when vaccinating persons at increased risk for bloodborne diseases such as HBV or human immunodeficiency virus (HIV) infection because of behavioral or other risk factors (emphasis added) (CDC, 1994).

The wordage within this report demonstrates CDC viewed the results of the Med-E-Jet and Ped-O-Jet were significant. For instance, breaking down the above sentence in bold will help clarify. “Laboratory studies [references CDC’s in vitro experiments on the Med-E-Jet and Ped-O-Jet] in which blood contamination of jet injectors [plural, thus referring to more than one brand of device] has been simulated have caused concern that the use of multiple-use nozzle jet injectors may pose a potential hazard of bloodborne-disease transmission.” Herein the CDC acknowledged results from both of these devices “caused concern” over transmission. It is also interesting to note the CDC acknowledged the potential that all “blood-borne” pathogens could be transferred via jet injection. Although Hepatitis C was known of during the time of this report, as Dr. Grabowsky had stated this was before universal precautions were instituted, not much was yet known about Hepatitis C, and CDC was investigating these risks on a disease by disease basis, so Hepatitis C was not intentionally omitted.

While CDC casted warnings concerning the risks of jet injectors, the agency also acknowledged the speed and cost-efficient benefits the devices brought to mass vaccination campaigns. With a reluctance in completely abandoning the technology the report also discussed ways the CDC believed consumers could minimize the risks associated with these devices.

Multiple-use nozzle jet injectors can be used in certain situations in which large numbers of persons must be rapidly vaccinated with the same vaccine, the use of needles and syringes is not practical, and state and/or local health authorities judge that the public health benefit from the use of the jet injector outweighs the small potential risk of bloodborne-disease transmission. This potential risk can be minimized by training health-care workers before the vaccine campaign on the proper use of jet injectors and by changing the injector tip or removing the jet injector from use if there is evidence of contamination with blood or other body fluid. In addition, mathematical and animal models suggest that the potential risk for bloodborne-disease transmission can be substantially reduced by swabbing the stationary injector tip with alcohol or acetone after each injection. It is advisable to consult sources experienced in the use of jet injectors (e.g., state or local health departments) before beginning a vaccination program in which these injectors will be used. Manufacturer’s directions for use and maintenance of the jet injector devices should be followed closely (CDC, 1994).

In the following years, CDC researchers spoke-out, warning of the risks posed by multi-use nozzle jet injectors. Dr. Bruce Weniger was the former Lead Researcher on Vaccine Technology within the CDC and one of—if not thee—leading expert on jet injection technology. Weniger compared CDC’s studies of the Med-E-Jet from 1986 and Ped-O-Jet from 1994. To recap, the jet injector nozzle was artificially contaminated and then fired into a vial. The ejectate fluid in the vial represents what would have been injected into the next person in the vaccination line. The data below shows the number of samples which tested positive for Hepatitis B surface antigen.

10- Weniger Slide Comparing CDC's Jet Injector Studies
(Weniger, 2003)

Dr. Weniger stated,

Comparing both the Med-E-Jet involved in the outbreak, in red on the right, with a Ped-O-Jet, in green on the left, they [CDC] were able to detect substantial proportions of the next injections from both devices, regardless of whether they followed manufacturer recommendations to swab or wipe the nozzles with acetone or alcohol before the next injection. As you can see, 38% and 6% of next injections with the Ped-O-Jet contained HBV, unswabbed or swabbed, respectively, compared to 80% and 64% of the outbreak-associated Med-E-Jet (emphasis added) (Weniger, 2005).

Indeed results of the Ped-O-Jet found rates of contamination lower than the Med-E-Jet, but contamination was exhibited nonetheless. As Dr. Weniger stated, CDC detected substantial proportions of Hepatitis B surface antigen within ejectates from both devices.

Former Deputy Director of CDC’s Hepatitis Laboratories Division Martin Favero, who had previously remained silent, voiced his concerns of jet injectors within a 1998 paper, titled, Potential for Cross-Contamination With Needleless Injector. Favero, along with his coauthor Pugliese, wrote,

Medical devices that are used on patients in fields containing potentially
infectious body fluids can become contaminated and transmit infectious agents to other sites on the patient or to other patients if the devices are not properly cleaned and sterilized or disinfected after each use. One such device is the needleless, or jet, injector, which is used widely in medicine and dentistry to deliver local anesthetic in procedures such as bone marrow aspirations, lumbar punctures, and cutaneous and intraoral injections (Pugliese & Favero, 1998).

Next Article –  Impact of CDC’s 1993-94 Unpublished Study – Part II


  • (CDC, 1994) Centers for Disease Control and Prevention. General Recommendations on Immunization: Recommendations of the Advisory Committee on Immunization Practices (ACIP). Morb Mortal Wkly Rep 43:(RR-1):7–8, 1994.
  • (Pugliese & Favero, 1998) Pugliese G., MS Favero. Potential for Cross-Contamination with Needleless Injector. Infection Control and Hospital Epidemiology. Nov. 1998. pg. 850.
  • (Weniger, 2003) Weniger BG. Jet Injection of Vaccines: Overview and challenges for mass vaccination with jet injectors. Innovative Administration Systems for Vaccines (conference). Rockville, Maryland, USA, 18-19 December 2003.
  • (Weniger, 2005) Weniger B. Safety of Multi-use-nozzle Jet Injectors (MUNJIs) for Bloodborne Pathogen Cross-contamination [draft]. Conference Notes. 7 August 2005.

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Brazilian Government Notes Risk of Ped-O-Jet Injectors: Prompts Investigations by CDC and WHO in the Early 1990s

The Brazilian Ministry of Health implemented safety testing upon Ped-O-Jet injectors in the late 1980s and early 1990s. The investigation was intended to uphold the safety of jet injectors but rather discovered the most widely-used device, the Ped-O-Jet, was a safety risk.

In 1987, a Measles Control Program was initiated within the São Paulo region of Brazil. A total of 8.7 million children aged nine-months to fourteen years were vaccinated with Ped-O-Jet injectors. Despite a hepatitis outbreak at a Los Angeles clinic with a Med-E-Jet injector, the healthcare workers in São Paulo believed the Ped-O-Jet was different and posed no risk (de Souza Brito, 1996).

The Brazilian Ministry of Health conducted a study to assure the safety of the Ped-O-Jet during routine military vaccinations in 1991 (de Souza Brito, 1996). The study aimed to answer three questions:

  1. What is the frequency of visible bleeding at the site of jet injection in the skin?
  2. What is the frequency of occult blood in the next vaccine shot dose?
  3. Is there any correlation between visible bleeding and occult blood of the next dose?

Glacus de Souza Brito and his fellow researchers led the investigation. It was observed amongst three vaccination sites the percent of vaccinees who bled immediately after the Ped-O-Jet was removed ranged from 2.2 to 23.3 percent. The average percent of bleeders was 3.6 percent (104 out of 2885). The researchers found “instantaneous bleeding took place after injection in a significant proportion of cases and that there was therefore a risk of downstream infection of subsequent subjects” (WHO, 1998).

The presence of blood prompted researchers to asses the possibility of cross-contamination. The subsequent shot after administering a vaccination was fired into a vial and analyzed. Amongst the three vaccination sites results detected blood within 0.2 to 6.6 percent of the ejectates, with the average being one percent (28 cases out of 2885 vaccinees).

The researchers found, “there was little to no correlation between visible bleeding and detection of occult blood in the successive vaccine doses. Only one person had both” (de Souza Brito et al., 1994; de Souza Brito, 1996). This finding is significant. There was no visible bleeding at the injection site in 27 out of 28 of the ejectates which contained blood, indicating blood transferred within microscopic levels not visible to the human eye.

Dr. Martin Friede of the WHO later noted, the researchers used blood detection stripes which can only detect around 2,000 picoliters of blood and therefore failed to detect blood within levels lower than 2,000 picoliters. The results demonstrated one percent of the ejectates contained 2,000 picoliters of blood (FDA, 2005). Therefore, the results found blood was being cross-contaminated via the Ped-O-Jet within volumes which could contain infectious viruses like Hepatitis B and Hepatitis C.

In 1992 a mass Measles Vaccination Campaign was launched across the entire country of Brazil. The government purchased 10,000 Ped-O-Jet injectors to vaccinate an estimated 50 million children between the ages of nine-months to fourteen years within a month period. During this mass vaccination campaign, a possible hepatitis B outbreak by Ped-O-Jet injectors was investigated but no statistical association was found. However, despite these findings the Brazilian government found the Ped-O-Jets were unsafe and stopped using the devices (Fields, 1996; de souza Brito, 1996).

These investigations by de Souza Brito were significant in raising safety concerns of jet injectors amongst the WHO and CDC. By 1994, Dr. de Souza Brito collaborated with researchers at the CDC to further investigate the inherent risks of Ped-O-Jet injectors. CDC Retests the Safety of Jet Injectors in 1993-94


  • (de Souza Brito, 1996) de Souza Brito G. Multi dose jet injectors and safety aspects in Brazil. CDC & WHO Meeting on Jet Injectors. Atlanta, October 2-3, 1996. (communication paper).
  • (de Souza Brito et al., 1994) de Souza Brito G, Chen RT, Stefano IC, Campos AM, Oselka G. The risk of transmission of HIV and other blood-born diseases via jet injectors during immunization mass campaigns in Brazil. 10th International Conference on AIDS, Yokohama, 7-12 August 1994;10(1):301 (abstract no. PC0132,
  • (FDA, 2005) FDA. General Hospital and Personal Use Devices Panel of the Medical Devices Advisory Committee. August 9, 2005. 35th Conference. Washington, D.C.
  • (Fields, 1996) Fields R. Participation in Meeting: Jet injectors for immunization; current practice and safety; improving designs for the future. WHO/CDC Meeting. Atlanta, GA. 2-3 October, 1996. Available at:
  • (WHO, 1998) World Health Organization. Technet Consultation. Expanded Programme on Immunization. Conference 16-20 March 1998. Copenhagen. WHO/EPI/LHIS/98.05.

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Analyzing CDC’s 1994 Conclusion

September 18, 2017

The Animal and Mathematical Models both demonstrated Ped-O-Jet injectors posed a risk in the transmission of blood-borne pathogens. The results also indicated wiping the nozzle only reduced and did not eliminate the risk. If the original design of this study were executed the results would have shown contamination of Hepatitis B surface antigen (HBsAg) in the internal fluid pathway, and that once the jet injector became contaminated it remained contaminated beyond the first shot and possibly beyond the second shot. Nonetheless, the evaluation showed sufficient levels of contamination for these CDC researchers to warrant restricted use of multi-use nozzle jet injector devices.

Grabowsky and colleagues recommended,

Jet injectors are most appropriate in emergency situations where mass vaccinations are required (e.g., meningitis outbreaks), in low HBV/HIV prevalence areas, or where other alternatives (e.g., disposable syringes) are unavailable or impractical. They should be avoided in some high risk groups or where proper cleaning and handling cannot be guaranteed. To reduce the risk of HBV or HIV transmission, the jet injector nozzle should be wiped after each injection with a rapidly drying agent (e.g., acetone). Use of a jet injector visibly contaminated with blood should be avoided (Grabowsky et al., 1994 [abstract]).

Grabowsky and colleagues openly admitted multi-use nozzle jet injectors (MUNJI) allowed the transfer of infectious pathogens between vaccinees and outlined what would be considered a low-risk circumstance when using a jet injector: Transmission would be considered low-risk when jet injectors are rarely used in emergency situations and amongst populations where the prevalence of blood-borne viruses (i.e., HBV, HCV & HIV) is low. Transmission would, therefore, be considered high-risk when MUNJIs are used repetitively amongst a population with a high prevalence of blood-borne pathogens, when nozzles are not wiped between vaccinees, and blood contamination upon the jet injector is disregarded.

MUNJI’s used within the military were used repetitively amongst an unscreened population. Military personnel were not screened for Hepatitis B, and Hepatitis C was not identified until 1989, although the virus has long existed. Therefore, there was no screening of military personnel for these viruses. Studies over the last twenty years have shown Vietnam-era and post-Vietnam era veterans have a higher prevalence of Hepatitis C than within the general population. The conditions of these veterans’ livers indicate they have had Hepatitis C for 30 to 40 plus years, dating back to the time of their military service. Archival footage has documented MUNJI nozzles were not wiped between vaccinees. Testimonies by thousands of veterans report the presence of blood upon the jet injector nozzle and at the injection site. These testimonies were later corroborated by an Armed Forces Epidemiological Board report which observed high-volume military jet injections and found “jet injector nozzle’s were frequently contaminated with blood, yet sterilization practices were frequently inadequate or not followed” (Department of Defense, 1999). Therefore, based upon CDC’s analysis of what is considered low risk it can be inferred the high-volume jet injections once conducted upon military personnel were high-risk.

Within Grabowsky’s conclusion, he also gives a precise explanation for the lack of cases implicating the use of jet injectors. “The detection of rare, silent transmission would have been difficult, however, and likely to have been missed without active surveillance” (Grabowsky et al., 1994). Here Grabowsky notes blood-borne pathogens, such as Hepatitis B and Hepatitis C, most often progress asymptomatically. There are no observable signs or symptoms indicating a person is infected. Detection would only be confirmed through a blood test, in which case was not possible for Hepatitis C until 1992. Therefore a person infected with Hepatitis B or Hepatitis C by a jet injector would more than likely not show initial signs or symptoms due to the asymptomatic progression of these viruses.

Moreover, his point that detection of jet injector transmission would only be seen through active surveillance is paramount in understanding the lack of documented cases implicating jet injectors.

The necessity for active surveillance in detecting jet injector transmission was not a new concept within CDC. In 1977 CDC’s Hepatitis Laboratories Division called for “specifically designed prospective seroepidemiologic studies” to assess the risk of hepatitis transmission via jet injectors. Yet no one heeded the call; not even the CDC. Apparently, this recommendation had fallen upon deaf ears too infatuated with the speed and cost-efficiency of MUNJI devices.

Shedding Light Upon What CDC Thought of Jet Injectors
Often I have wondered what researchers within CDC actually thought of the risks associated with jet injectors. Did CDC view jet injectors as being only “theoretically” unsafe? Or did CDC view the risks associated with the Ped-O-Jet as real?

I reached-out to Dr. Mark Grabowsky, who is now retired, to help shed some light upon this third evaluation.

Dr. Grabowsky clarified his 1994 unpublished CDC study “was basically a literature review for internal CDC use looking at published data on jet injector safety.”

Below is part of our interview. As Dr. Grabowsky noted, these are only his “personal opinions and wild-ass-guesses without looking further into it.”

Q. How unsafe did CDC view these devices?

A. “We saw them as unacceptably unsafe,” stated Grabowsky. “It was because of the serum blowback and contamination of the tips of the devices. It was in the early days of HIV so we were all a little more worried. New devices with disposable tips or one-way valves were seen as more acceptable.”

Q. Throughout the 1990s the CDC warned of the risk of jet injectors transmitting Hepatitis B virus and HIV. Why didn’t the reports include the Hepatitis C virus? Personally, I always believed it was because the Hepatitis C virus was relatively new to medical professionals and still not understood very well but this is just my opinion.

A. “I think that is right.  We just never knew much about Hepatitis C at that time.  It was also really before the era of universal precautions so we were taking it on a disease by disease basis.”

Q. Do you think Hepatitis C could have been transmitted via jet injectors?

“I assume that if it was around it would have been transmitted.”

Q. Unequivocally, CDC has deemed multi-use nozzle jet injectors pose a risk in transferring blood-borne pathogens and has discouraged the use of these devices. Yet the agency has never recognized jet injectors as a risk factor for Hepatitis B, Hepatitis C, or HIV. Why do you think this is?

A. “At the time, I think it was because these types of injectors were being removed from use and so weren’t present as a risk factor.  But we certainly would have checked with the military and others who were using them.”

Q. Did CDC believe there was a lack of epidemiological evidence for listing jet injectors as a risk factor?

A. “I think the evidence was clear they were a risk – which is why the types of injectors were not in use.”

Q. Did CDC believe there was a lack of research for listing jet injectors as a risk factor?

A. “Probably lack of priority in identifying rare and hard to detect events that were going away anyway as jet injector use faded.”

As Dr. Grabowsky stated CDC viewed MUNJI devices as “unacceptably unsafe” due to serum blowback and contamination on the nozzle tips. In his professional opinion, he believes the Hepatitis C virus “would have been transmitted” via jet injection just like any other blood-borne pathogen.

What impact did the results of this third evaluation into jet injectors make?

Next Article – Impact of CDC’s 1993-94 Unpublished Study – Part I


  • (Department of Defense, 1999) Department of Defense. C. Issues of administration, 1. Jet injector use. In: Poland GA, (ed.). Vaccines in the Military: a Department of Defense-wide Review of Vaccine Policy and Practice. A Report for the Armed Forces Epidemiological Board, August 1999. Falls Church, VA: Infectious Diseases Control Subcommittee of the Armed Forces Epidemiological Board, 1999;60.
  • (Grabowsky et al., 1994) Grabowsky M, Hadler SC, Chen RT, Bond WW, de Souza Brito G. Risk of transmission of hepatitis B virus or human immunodeficiency virus from jet injectors and from needles and syringes. Unpublished manuscript draft, dated January 3, 1994.
  • (Grabowsky et al., 1994 [abstract]) Grabowsky M, Hadler SC, Chen RT, Bond WW, de Souza Brito G. Risk of transmission of hepatitis B virus or human immunodeficiency virus from jet injectors and from needles and syringes [abstract]. 1994.

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CDC’s Animal and Mathematical Models

September 15, 2017

Animal Model
Grabowsky and colleagues utilized an animal model to assess the degree of contamination from a Ped-O-Jet injector. Two sets of in vitro tests were conducted to measure the frequency and volume of Hepatitis B surface antigen. The first test measured the degree of contamination when the gun was used according to the manufacturers recommendations. The second test measured the degree of contamination when the nozzle was wiped after administering an injection. These tests were similar to previous jet injector experiments conducted by CDC in 1977 and 1986, thanks in part to Walter Bond who served within all three experiments.

First Test
Within the first test, the researchers assessed whether after firing the Ped-O-Jet if the Hepatitis B surface antigen (HBsAg) would be sucked into the nozzle orifice and contaminate the next dosage. Detection of HBsAg would be indicative of Hepatitis B transmission.

For this experiment, the underside of a rabbit was shaved five days prior to testing. Upon the day of the experiment the rabbit was euthanized and 0.025 milliliters of HBsAg serum was placed upon the shaved skin of the rabbit. A sterile Ped-O-Jet administered a 0.5 milliliters injection to the now HBsAg-contaminated underbelly of the rabbit. Following the injection, the gun was held in place for 2 to 3 seconds, per manufacturer’s instructions. The Ped-O-Jet was then fired once into five separate 1 dram vials. The ejected fluid within each of the five vials was tested for HBsAg using Radioimmunoassay Ausria II. The test was repeated ten times creating a total of 50 samples. Every time the test was repeated the Ped-O-Jet was sterilized through autoclaving (Grabowsky et al., 1994).

The Ausria II Radioimmunoassay to detect Hepatitis B surface antigen was the same radioimmunoassay used within the 1977 investigation. It remains unclear why the researchers did not use newer, more sensitive radioimmunoassays able to detect far lower levels of HBsAg. The fact that Ausria II was used again was likely the decision of Walter Bond who served within both investigations of the Ped-O-Jet.

Nonetheless, the results found the ejected fluid of the next shot fired was positive for HBsAg in 19 out of 50 (38%) of the samples. Within these contaminated samples, the average volume of blood detected in the ejectate was 0.118 microliters (range, 0.023 uL – 0.417 uL) (Grabowsky et al., 1994). The exterior nozzle of the Ped-O-Jet was positive for HBsAg in 8 out of 10 (80%) of the samples. Yet the interior of the nozzle was negative (0 out of 10) for HBsAg contamination (Weniger, 2003). This data demonstrated significant contamination.

To put this into perspective, lets convert these figures into picoliters which is the smallest estimated unit for transferring blood-borne pathogens. One microliter equals 1,000,000 picoliters. The estimated volume of blood to transfer the Hepatitis B particles is 10 picoliters and the estimated volume of blood to transfer Hepatitis C particles is 100 picoliters.

Therefore, the contaminated 19 samples of ejected fluid converts to 23,000 to 417,000 picoliters of blood, with the average volume of blood being 118,000 picoliters. This means these samples could hold 2,300 to 41,700 Hepatitis B particles and 230 to 4,170 Hepatitis C particles. With the averages being 11,800 Hepatitis B particles and 1,180 Hepatitis C particles. This data demonstrates blood-borne pathogens could have been transferred through the ejectate fluid of a Ped-O-Jet injector.

Second Test
In a second set of tests, the researchers assessed whether wiping the nozzle reduced or prevented cross-contamination between jet injections. The nozzle of the Ped-O-Jet was wiped with a cotton ball moistened in acetone immediately after inoculating the underside of a rabbit contaminated with 0.025 milliliters HBsAg serum. The Ped-O-Jet was then fired five times into five separate 1 dram vials. The ejectate fluid in each of the vials was assayed. This test was repeated ten times (Grabowsky et al., 1994).

Results found the ejected fluid of the next shot fired was positive for HBsAg in 3 out of 50 (6%) of the samples. Within these contaminated samples, the average volume of blood detected in the ejectate was 0.016 microliters (range, 0.01 uL – 0.022 uL) (Grabowsky et al., 1994). The exterior nozzle of the Ped-O-Jet was positive for HBsAg in 3 out of 10 (30%) of the samples. While the interior of the nozzle was again negative (0 out of 10) for HBsAg contamination (Weniger, 2003).

To put this into perspective, the contaminated 3 samples of ejected fluid converts to 10,000 to 22,000 picoliters of blood, with the average volume of blood being 16,000 picoliters. This means these samples could hold 1,000 to 2,200 Hepatitis B particles and 100 to 220 Hepatitis C particles. With the averages being 1,600 Hepatitis B particles and 160 Hepatitis C particles. The data demonstrates wiping the nozzle of the Ped-O-Jet reduced but did not eliminate contamination, and thus blood-borne pathogens could still have been transferred.

Limitations of Study
In reviewing this study, it came to the attention of this author that the researchers had failed to collect all of the data as planned within the original design of their study. After artificially contaminating the Ped-O-Jet, the gun was to be “shot” five consecutive times, each time into a 1 dram vial so the ejectate of the “shot” could be collected and assayed. Therefore the first “shot,” represents the first injection given after the jet injector became contaminated. The second, third, fourth and fifth shots represent the second, third, fourth and fifth persons to receive an injection after the jet injector became contaminated. This test was repeated ten times; thus creating 50 samples. However, Grabowsky and colleagues failed to assess and report how many of the HBsAg-positive samples were from the first shot, how many from the second shot, how many from the third shot, and so forth. The graph below demonstrates how the test should have been conducted. This data would be important in identifying how long the Ped-O-Jet remain contaminated, as was done within CDC’s 1977 evaluation.

Recommended Graph

For instance, in the first test 19 of the 50 samples were HBsAg-positive indicating that more than just the first shots were contaminated. We can presume that all ten of the first shots were positive and therefore either nine of the second shots tested were positive or eight of the second shots and one of the third shots were positive, etc. This information would have been very beneficial for assessing the degree of contamination.

Moreover, the data indicating the interior of the nozzle was negative for HBsAg contamination zero out of ten times is misleading. The experiment was repeated ten times. Therefore it can be assumed that the interior nozzle was only tested in each of the ten experiments after firing the fifth shot into the vial. Yet, as CDC’s 1977 experiment found, once the Ped-O-Jet became contaminated it remained contaminated for the following two consecutive shots. So the researchers should have analyzed within a third set of tests how many of the samples would be positive for HBsAg if the interior of the nozzle was tested after the first or second shots. Based upon the design of their study, they only assessed if the jet injector was still contaminated after firing five shots. The researchers failed to assess the risk to the next person in line once the jet injector became contaminated.

Mathematical Model
Grabowsky and colleagues (1994) also assessed the risk of blood-borne disease transmission via jet injectors and needle stick injuries by implementing a mathematical model. This equation is being thoroughly analyzed and scrutinized and will be reported upon at a later date.

From the Animal and Mathematical Models Grabowsky and colleagues summarized their findings. Join us Monday, September 18th to read Analyzing CDC’s 1994 Conclusion.


  • (Grabowsky et al., 1994) Grabowsky M, Hadler SC, Chen RT, Bond WW, de Souza Brito G. Risk of transmission of hepatitis B virus or human immunodeficiency virus from jet injectors and from needles and syringes. Unpublished manuscript draft, dated January 3, 1994.
  • (Weniger, 2003) Weniger BG. Jet Injection of Vaccines: Overview and challenges for mass vaccination with jet injectors. Innovative Administration Systems for Vaccines (conference). Rockville, Maryland, USA, 18-19 December 2003.

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Part 3 – CDC Retests the Safety of Jet Injectors in 1993-94

September 12, 2017

In 1993, the Center for Disease Control and Prevention (CDC) retested the safety of the most widely-used jet injector—the Ped-O-Jet. The investigation was the agency’s second evaluation into Ped-O-Jet, and third overall evaluation of jet injector devices.

The ongoing investigation into jet guns was prompted by three circumstances: 1) An increased awareness of HIV and viral hepatitis, which had caused a growing fear of virus transmission within the medical community at the time; 2) Two previous CDC investigations (i.e., 1977 and 1986) failed to demonstrate jet injectors were risk free; and 3) Investigations of the Ped-O-Jet in Brazil in 1991 detected blood within the subsequent shots which were not associated with visible bleeding.

“As part of an ongoing epidemiologic investigation of HBV [Hepatitis B] transmission involving use of a jet injector,” wrote lead CDC researcher Dr. Mark Grabowsky in an unpublished study, “we conducted comparative laboratory studies to examine the potential risk of the transmission of bloodborne viruses should the injector become contaminated” (Grabowsky et al., 1994). The findings, although never published, were not kept a secret and an abstract was made known to the public in the Spring of 1994.

Jet Infectors - CDC's 1994 Study

Amongst Grabowsky’s team were: Epidemiologists, Dr. Stephen Hadler and Dr. Robert Chen, from CDC’s National Immunization Program; microbiologist, Walter Bond from CDC’s Hospital Infections Program; and epidemiologist Dr. Glaucus de Souza Brito from the Brazilian Ministry of Health.

Many of researchers had previous experience in assessing the safety of jet injectors. Dr. Hadler was a part of CDC’s evaluation of the Med-E-Jet in 1986. Dr. de Souza Brito had extensively used and tested the Ped-O-Jet in Brazil. Most interestingly though, Mr. Bond had been involved within all three of CDC’s safety testing of jet injectors.

In this third evaluation CDC sought “to estimate the risk of bloodborne disease transmission from a jet injector” and to determine if swabbing the Ped-O-Jet injector nozzle had an effect on reducing the risk of transmission (Grabowsky et al., 1994).

It is important to note a major shift in the rhetoric by CDC. As noted above, the CDC stated its purpose was to assess the “risk of bloodborne disease transmission from a jet injector” (Grabowsky et al., 1994). However, four-years prior, CDC researchers Canter and colleagues (1990), recommended “training in the use of jet injectors, and care in cleaning and disinfection procedures to ensure the continued safe use of these instruments” (Canter et al., 1990). Within a time period of four-years, the CDC went from “the continued safe use” of jet injectors to estimating the “risk of bloodborne disease transmission from a jet injector.”

Overview of Study
Unequivocally, CDC knew jet injectors could act as vehicles in the transfer of pathogens. CDC also knew these devices posed a risk especially amongst highly infectious viruses. “It was estimated that viruses that circulate in high titers in blood, such as HBV (10x-8/ml) and LDH virus (10x-7/ml), could be transferred during a procedure if the jet injector were contaminated during use,” stated Grabowsky in reviewing CDC’s 1986 investigation of the Med-E-Jet (Grabowsky et al., 1994).

The time had come to assess how much of a risk the Ped-O-Jet posed. Grabowsky and colleagues used two methods to assess this risk: an Animal Model and a Mathematical Model.

What did Grabowsky’s investigation reveal? CDC’s Animal and Mathematical Models


  • (Canter et al., 1990) Canter J, Mackey K, Good LS, Roberto RR, Chin J, Bond WW, Alter MJ, Horan JM. An outbreak of hepatitis B associated with jet injections in a weight reduction clinic. Arch Intern Med. 1990 Sep; 150(9):1923-7.
  • (Grabowsky et al., 1994) Grabowsky M, Hadler SC, Chen RT, Bond WW, de Souza Brito G. Risk of transmission of hepatitis B virus or human immunodeficiency virus from jet injectors and from needles and syringes. Unpublished manuscript draft, dated January 3, 1994.

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L.A. County Health Dept. Knew Ped-O-Jet Injectors Produced Blood in 1974

In 1974 the Los Angeles County Health Department implemented a mass jet injection vaccination campaign aimed to protect persons 65 years of age and older from influenza. The Clinic Manual for this event documented the protocols of a mass jet injection campaign and sheds light upon what these professionals knew about the presence of blood when using a Ped-O-Jet injector.

Within the manual, given to each volunteer, were instructions on the correct usage and trouble shooting of Ped-O-Jet injectors and specific instructions on the roles of the vaccination team.

Instructions For Use of Jet Injector Apparatus (Ped-O-Jet and Electric Models)

Most shockingly, within the instructional sheet for jet injectors is the omission that “Many patients will have a drop of vaccine and a drop of blood remaining on the arm after injection.” Here, during the wide-spread use of jet injectors, is acknowledgment that blood remained on the arm after injection. In other words, blood was on the arm while the nozzle of the jet injector was pressed upon the skin. Moreover, there is acknowledgment that the presence of blood was observed amongst many patients. Therefore, the jet injector was frequently exposed to blood during the vaccination campaign.

Jet Infectors - 1974 Ped-O-Jet Injector Manual Instructions

Just as appalling, under the heading “Common Errors to Avoid While Using Jet Injector,” is the instruction to “Never swab injector nozzle with cotton.” But no explanation is given as to why. Presumably a cloth could be used. Although the impression given within the manual connotes the nozzle should not be swabbed at all.

Jet Infectors - 1974 Common Jet Injector Problems and Remedies

Roles of the Vaccination Team
Amongst the roles of the vaccination team were the Gun Operator and Arm Inspector.

Gun Operator
1. Be responsible for giving the injections with the jet injection gun. RN’s and LVN’s will function as gun operators.
2. Inject immunization subcutaneously into the outer aspect of upper arm (see gun Instruction sheet). The injection site will have been prepared with acetone or other disinfectant by a volunteer.
3. See that an emergency kit is located near the guns. Each nurse should be familiar with the contents of the kit and its use. (Instructions are on the kit.)

Arm Inspector
Special Consideration: Leave adequate space between you and the gun operator’s station.

1. Place a cotton ball on the injection site and ask the patient to hold it tightly with the opposite hand.
2. Send the patient to the next station for an aftercare sheet.

It is important to point-out, after each injection a cotton ball was to be held firmly upon the injection site. The only reason to apply pressure to a vaccination site would be to stop bleeding.

Jet Infectors - 1974 Clinicians Manual on Jet Injector Use

The 1974 Los Angeles County Mass Influenza Campaign
The campaign came following the swift passing of the Thurman Act (California Bill AB-3157), which aimed to “provide an annual vaccination to populations having excess mortality rates from influenza complications.” At the time the elderly were the most at risk population.

Floyd Irons, in fulfilling his thesis for a master’s degree from California State University, documented the planning and implementation of this mass influenza vaccination campaign.

The planned three-day event across 150 locations was made possible through implementing 50 electric and foot pedal Ped-O-Jet devices. Through Irons’ thesis is a glimpse at how many Ped-O-Jet devices were owned by various government health agencies.

Los Angeles County maintains a stock of 15 guns, and the remainder of the 50, plus additional back-up guns [5-8 guns] would be borrowed from the Sate Department of Health and from neighboring states, as well as the Center for Disease Control in Atlanta.

The Health Department scheduled the mass vaccination campaign across three Thursdays within October of 1974 (Oct. 10th, 17th and 24th). The schedule also listed the Ped-O-Jets were to be sterilized by autoclaving only once on Oct. 9th.

Today a greater understanding of the inherent risks of jet injectors exist. These devices have been documented in transferring blood and blood-borne pathogens in microscopic levels not visible to the human eye. Even when these devices were used properly they still posed a risk. So the following is a moot point but nonetheless is still worth asking:
Why were the jet injectors, which were repeatedly exposed to blood, not autoclaved before the subsequent vaccination events?

Why didn’t the instructions state if the jet injector were to become contaminated with blood the gun should be removed from operation and sterilized?

Yet nowhere in the manual were instructions for removing and autoclaving jet injectors contaminated with blood.

Irons’ thesis has documented how jet injectors were used within a mass vaccination campaign. Moreover, his thesis serves as evidence that in the mid-1970s healthcare professionals knew Ped-O-Jet injectors caused patients to bleed during and after the injection. Nowhere in his thesis were any measures to prevent the transference of blood between patients. At the time knowledge of blood-borne pathogens was primitive, however since the mid-1950s medical professionals highly cautioned of the risk for transferring hepatitis and malaria from blood-to-blood contact. Therefore, there was a clear disregard for the risk of transferring blood to subsequent vaccinees within this vaccination campaign.

A copy of Floyd Irons 1976 these can be assessed here.

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Impact of the 1985 Outbreak

For the past thirty-one years, the CDC led the public to believe that the 1986 report was the agency’s first investigation into jet injectors. The CDC assured that this outbreak was only due to the particular nozzle design of the Med-E-Jet and that all other jet injectors were safe. Omitted from any discussion or report was the fact that the agency had conducted safety testing of the Ped-O-Jet nine-years prior and found transmission was possible. Regardless of the 1985 outbreak, the CDC continued to use multi-use nozzle jet injectors.

Within the Department of Defense, the outbreak prompted the Armed Forces Epidemiological Board (AFEB) to discuss the risks of jet guns in a July 1st, 1986 meeting (Federal Register, 1986). The AFEB is an expert advisory board of civilian physicians and scientists that assists the Department of Defense with medically related issues. The AFEB even discussed the possibility of HIV being transmitted when jet injectors administer biological products, such as gamma globulin.

…the Board stated that the chance of transmitting HIV infection through gamma globulin given by jet injector was too remote to be significant. Those persons most responsible for formulating these decisions and recommendations had previously had extensive experience with the jet injector; Dr. Abram Benenson had worked with it since it was developed (Woodward, 1990).

However, here the AFEB’s conclusion was based upon outdated information. An extensive review of the literature on Dr. Abram Benenson and jet injectors reveals that the last time Dr. Benenson was involved in any safety testing of jet injectors was in 1959 during his employment with Walter Reed Army Institute of Research. Papers, either authored or co-authored by Benenson, and the commissions and committees in which he had served since 1959 only assessed the efficacy of the vaccines administered by jet injection and did not assess the safety of jet injector devices. Therefore, the AFEB’s basis for their decision was relied upon Dr. Benenson’s experience from 27-years prior.

Moreover, Jet Infectors review of the literature has found Dr. Benenson should have reached a conclusion contrary to his 1985 opinion. Personal statements previously made by Benenson are inconsistent with his 1985 opinion. These statements and instances include:

  • In a 1968 paper, Dr. Benenson disclosed “Difficulty was encountered with one of the jet injectors…” and reported, “all of the Pakistani employees of this laboratory developed an area of erythema at the site of jet injection…” (Benenson, Joseph & Oseasohn, 1968). The occurrence of erythema, superficial reddening of the skin as a result of injury causing dilatation of the blood capillaries, should have prompted an investigation into the risk of cross-infection, as well as questioned the sterility of this procedure.
  • In 1971, Dr. Benenson attended a NIH conference on the efficacy of tuberculosis vaccinations. During this conference, Dr. Sol Roy Rosenthal noted blood during the mass vaccination of school children and noted the potential for the transference of hepatitis. The committee for which Dr. Benenson was a part of concluded, in regards to jet injection, “The possibility of transfer of infectious hepatitis, however, is not excluded” (DHEW, 1972).
  • In 1978, Dr. Benenson attended a conference held by the AFEB on Leishmania skin testing. Benenson considered using jet injectors to conduct a Leishmania test upon military personnel but said “I have looked at it as a practical procedure using the intradermal gadget on the jet injector which is not 100 percent” (AFEB, 1978).

Dr. Benenson had previously found jet injector devices to be “not 100 percent,” induced erythema at the site of injection, and had agreed with fellow conference members that due to the presence of blood during jet injections the risk of transferring hepatitis cannot be exlcuded.

Despite the in depth discussions the committee was reluctant to impose any changes in July of 1986 (Federal Register, 1986; Woodward, 1990). By 1987 the AFEB finally recommended the Med-E-Jet be banned within the Armed Forces and be removed from the Federal Stock System (Nikolewski & Wells, 1989). In March of 1988, the AFEB gave the recommendation “that the jet injector gun be used only with authorized military technical parts and that it be sterilized according to standard procedures” (Woodward, 1990).

Regardless of the AFEB’s recommendation that jet injector devices be autoclaved and used in accordance with “standard procedures” the Armed Forces continued to use jet injectors haphazardly. Military footage and a subsequent AFEB report in 1999 document the military’s disregard for abiding standard procedures and set protocols for sterilization.

Outside of the United States, the 1985 outbreak elicited a far different response. For many the outbreak served as proof that all multi-use nozzle jet injectors were unsafe and served as a catalyst for change.

In September of 1986, a Dutch committee on immunization opined that jet guns should no longer be used in the Netherlands (Bijkerk, 1986). The decision stemmed not only from the 1985 U.S. outbreak but also from a Dutch study by Brink and colleagues (1985) which demonstrated virus transmission from the use of jet guns.

By October of 1986, the World Health Organization (WHO) changed its policy on jet injector usage. WHO’s highly publicized statement said,

Until further studies clarify the risks of disease transmission associated with jet injectors, general caution in their use is recommended (WHO, 1986).

Their use should be restricted to special circumstances where the use of needles and syringes is not feasible because of the large numbers of persons to be immunized within a short period of time (WHO/UNICEF, 1987).

This change restricted the use of jet injectors to dire situations only.

By 1989, both UNICEF and WHO recommended establishing stricter safety guidelines for jet injectors. One recommendation addressed correcting an inherent problem with jet injectors. “[The] manufacturer must provide evidence that there shall be no reflux of external fluid into the fluid path way after repeated injections,” stated the report (UNICEF/WHO, 1989). Herein UNICEF and WHO identified the inherent problem of fluid suck-back and the risk of virus transmission this posed. It is important to note, fluid suck-back was observed in CDC’s 1977 investigation of the Ped-O-Jet and in CDC’s 1986 investigation of the Med-E-Jet.


  • (AFEB, 1978) Armed Forces Epidemiological Board. Proceedings of the Armed Forces Epidemiological Board Ad Hoc Subcommittee on Leishmaniasis. Washington, D.C. 11 April 1978.
  • (Benenson, Joseph & Oseasohn, 1968) Benenson, A.S., Joseph P.R., R.O. Oseasohn. Cholera Vaccine Field Trials in East Pakistan. 1. Reaction and antigenicity studies. Bull. Wld Hlth Org. 1968, 38, 347-357.
  • (Bijkerk, 1986) Bijkerk H. Het risico van ziekte-overdracht via een inentingspistool bestaat. [Risk of Disease Transmission Via Jet Gun Injection is Real]. Ned Tijdschr Geneeskd. 1986 Nov 8;130(45):2050. [article in Dutch]
  • (Brink et al., 1985) Brink PRG, van Loon AM, Trommelen JCM, Gribnau FWJ, Smale-Novakova IRO. Virus transmission by subcutaneous jet injection. J Med Microbiol. December 1985; 20(3): 393-397.
  • (DHEW, 1972) Department of Health, Education and Welfare, Public Health Service, National Institutes of Health. Status of Immunization in Tuberculosis in 1971; DHEW Publication No. (NIH) 72-68, pp. 185-187. Washington, D.C., 1972.
  • (Federal Register, 1986) Armed Forces Epidemiological Board; Open Meeting. 51 Fed. Reg. 108 (June 5, 1986). Federal Register: The Daily Journal of the United States. 5 June 1986.
  • (Nikolewski & Wells, 1989) Nikolewski RR & Wells RA. “Appendix 3: A List of the Board’s Recommendations from 1955 through 1989.” The Armed Forces Epidemiological Board: It’s First Fifty Years. Available online:
  • (UNICEF/WHO, 1989) UNICEF/WHO. Criteria for low-workload jet injectors: May 11, 1989, J. Bish UNICEF and RH Henderson, WHO/EPI.
  • (WHO, 1986) WHO/EPI. WHO/UNICEF Joint Guidelines. Selection of Injection Equipment for the Expanded Programme on Immunization. 1986. WHO/UNICEF/EPI.T5/ 86.27597.
  • (WHO/UNICEF, 1987) WHO/UNICEF. Expanded Program on Immunization-Joint WHO/UNICEF Statement on Immunization and AIDS. 1987. pp 18-19.
  • (Woodward, 1990) Woodward TE. The Armed Forces Epidemiological Board: Its first fifty years. Center of Excellence in Military Medical Research and Education. 1990.

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Part 2 – CDC Retests the Safety of Jet Injectors in 1986

June 19, 2017

“Hepatitis Outbreak Laid to Contaminated Jet Injection Gun,” read the headline of the June 13th, 1986 edition of the LA Times (Maugh, 1986).  Between 1985 and 1986, the CDC thoroughly investigated a Hepatitis B outbreak caused by a jet injector at a LA weight reduction clinic.

Assessing the Outbreak
The weight reduction clinic in Long Beach was administering regular injections of human chorionic gonadotropin (HCG) to its patients via a Med-E-Jet injector and by syringe and needle at the time the outbreak was identified by local health officials.

Analyses by CDC found twenty-one percent (60/287) of those attending the clinic had an acute infection of Hepatitis B.  Twenty-seven individuals were infected with Hepatitis B and another thirty-three individuals were IgM positive meaning each had the antibody to hepatitis B core antigen (Canter et al., 1990; CDC,1986).  For a person to test IgM positive is indicative that he or she was infected with the hepatitis B virus within the last 6-months.  Two individuals identified with Hepatitis B were found to have other risk factors for acquiring Hepatitis B virus within the previous six-months (CDC, 1986).  Therefore, two individuals already infected with Hepatitis B were identified amongst the cohort receiving jet injections and were likely the culprits who unknowingly infected the others.

Amongst those individuals who exclusively received HCG by jet injection, twenty-four percent (57/239) had developed an acute Hepatitis B virus infection.  Interestingly, the 22 patients who received injections exclusively by a syringe never acquired the hepatitis B virus (CDC, 1986; Canter et al., 1990).  This data indicates that a total of 57 individuals had evidence of acute infection with hepatitis B virus as the result of receiving injections with a multi-use nozzle jet injector.

“Everyone always assumed that jet guns were safe,” said Dr. Steve Hadler, Chief of Epidemiology Activity within CDC’s Hepatitis Branch, in a newspaper article (Hendrick, 1986).

CDC’s assessment of the outbreak found 57 individuals had been infected from receiving injections with a jet injector.  Throughout the years, the Department of Veterans Affairs (VA) has grossly minimized this outbreak. VA states, “there is at least one case report of hepatitis B being transmitted by an airgun injection” (VBA Fast Letter 211 (04-13)).  A case report is defined as a detailed report listing the signs, symptoms, diagnosis and treatment of an individual patient.  Therefore, contrary to VA’s reporting, there are in actuality 57 documented cases, or rather 57 cases reports, of Hepatitis B being transmitted by jet injection.

The outbreak prompted CDC to retest the safety of jet injectors.

CDC’s Laboratory Investigations
“Five Med-E-Jet injectors used in these weight reduction clinics were sent to the Centers for Disease Control, Atlanta, Ga, for further evaluation,” stated a report by the researchers (Canter et al., 1990).

CDC’s 1986 investigations evaluated the threat of cross-contamination of blood-borne pathogens when using a Med-E-Jet injector.  The researchers explained their 1986 investigations within a medical journal.  “A series of in vitro and in vivo laboratory experiments were carried out to assess the potential for a contaminated Med-E-Jet to transmit HBV from patient to patient and to assess the potential for HBsAg contamination of this jet injector during actual use,” stated the article (Canter et al., 1990).  Within these experiments detection of the Hepatitis B surface antigen (HBsAg) would be presumptive evidence of Hepatitis B contamination.

Analysis of the outbreak and investigations of the Med-E-Jet were published twice; once within a 1986 CDC report and again in a 1990 medical journal.  It is interesting to also note that CDC microbiologist Walter Bond, who was a part of the 1977 investigations of the Ped-O-Jet, was also a part of the 1986 laboratory investigations of the Med-E-Jet in Atlanta.

Firing Into Vials – In Vitro Experiments
Several in vitro tests were implemented to assess the frequency of contamination when using the Med-E-Jet.  Within the first experiment, the Med-E-Jet nozzle was artificially contaminated with Hepatitis B surface antigen (HBsAg) to see if the antigen would be sucked back into the nozzle head and contaminate the next dosage to be fired.
Results found, after the nozzle was contaminated, the ejected fluid of the next shot fired was positive for HBsAg in 40 out of 50 (80%) of the samples.  Med-E-Jet surfaces were also tested for contamination.  Results showed HBsAg contamination upon the exterior of the nozzle in 9 out of 10 (90%) of the samples.  Samples from within the nozzle interior were HBsAg-positive in 8 out of 10 (80%) occurrences.  The nozzle tip was HBsAg-positive in 9 out of 10 (90%) of the samples (Weniger, 2003).  This data demonstrated gross contamination of the Med-E-Jet due to fluid suck-back.

In a second set of experiments, researchers assessed if wiping the nozzle between consecutive patients would remove any contamination from the nozzle surface.  Using a cotton ball moistened in acetone researchers wiped the contaminated Med-E-Jet nozzle to see if the HBsAg would be reduced or eliminated.

The results after wiping the nozzle found the ejected fluid of the next shot fired was positive for HBsAg in 29 out of 45 (64%) of the samples.  Results of Med-E-Jet surfaces were positive for HBsAg in 7 out of 9 (78%) of the samples from the nozzle exterior, 5 out of 9 (56%) of the samples from the nozzle interior, and 6 out of 9 (67%) of the samples from the nozzle tip.  This data indicated wiping the Med-E-Jet with acetone after each injection did not significantly reduce the frequency of HBsAg contamination (Weniger, 2003).

Jet Injecting Chimpanzees – In Vivo Experiments
In this in vivo experiment the CDC assessed if the Med-E-Jet would become contaminated with Hepatitis B surface antigen after injecting a chimpanzee infected with the pathogen.  Immediately following the injection the next shot to be delivered was fired into a vial and tested for blood and HBsAg.  This test was repeated five times.

Results could not detect HBsAg in the ejected fluid in any of the five injections with the Med-E-Jet.  The researchers, however, did state, “Bleeding did occur at the four of the five injection sites, even though injections were carefully done according to the manufacturer’s recommendation” (Canter et al., 1990).

Despite these findings it is duly noted that the exact Med-E-Jet injectors documented in the 1985 Hepatitis B outbreak of 57 individuals did not demonstrate such cross-contamination when tested upon a chimpanzee.  This finding calls into question the validity of relying upon chimpanzee studies to assess the safety of jet injectors.  It appears, in this regard, comparing humans to chimpanzees is like comparing apples to oranges.

Possibly the assay used by CDC within their laboratory investigations was not able to detect HBsAg.  The report did not specifically mention which assay product was used within the laboratory investigations.  Although it was noted that within the investigation of the outbreak serum specimens of those attending the Long Beach clinic were evaluated using Auszyme by Abbott Laboratories (Canter et al., 1990).  Assuming the assays were the same for both procedures would call into question the validity of the animal model used.  If the assays were different it would call into question the capability of the assay used within the laboratories investigation to detect low levels of HBsAg.

Summary of Findings
In 1986, the CDC investigated the Med-E-Jet in a laboratory setting to assess the degree of contamination caused by this particular model of device.  The official 1986 report stated,

the estimated volume of contaminating material transferred in downstream injections was 0.53 micro liters (0.53 x 10–3ml).  Therefore, it can be estimated that viruses that circulate in high titers in blood, such as HBV (10-8/ml) and LDH virus (10-7/ml), could be transferred during a procedure if gun contamination occurred.  The probability of transferring microorganisms present in lower concentration ( < 10-3/ml) would be correspondingly lower (CDC, 1986).

Herein the CDC recognizes highly infectious viruses can be transferred via jet injection.

Canter and colleagues (1990) concluded, “This epidemiologic and laboratory investigation suggests that when this model of jet injector [Med-E-Jet] becomes contaminated with blood, transmission of HBV can occur” (Canter et al., 1990).

A newsletter submitted within a congressional hearing on HBV remarked of Canter and colleagues, saying, “The CDC proved that such a jet injector could transmit HBV despite proper swabbing of the tip, due to the inaccessability of contaminated surfaces under the nozzle and cap” (U.S. Congress, 1999).


  • (Canter et al., 1990) Canter J, Mackey K, Good LS, Roberto RR, Chin J, Bond WW, Alter MJ, Horan JM. An outbreak of hepatitis B associated with jet injections in a weight reduction clinic. Arch Intern Med. 1990 Sep; 150(9):1923-7. 
  • (CDC, 1986) Centers of Disease Control. Epidemiologic Notes and Reports Hepatitis B Associated with Jet Gun Injection — California. MMWR 1986;35(23):373-376.
  • (Hendrick, 1986) Hendrick O. Jet gun injector causes hepatitis outbreak. United Press International 12 June 1986. Accessed at:
  • (Maugh, 1986) Maugh TH. Hepatitis outbreak laid to contaminated jet injection gun. Los Angeles Times. 13 June 1986. Accessed at:
  • (U.S. Congress, 1999) United States. Committee on Government Reform. Hearings, 18 May 1999. 106th Cong. 1st sess. Washington: GPO 2000.
  • (VBA Fast Letter 211 (04-13)) VBA Fast Letter 211 (04-13). Relationship Between Immunization with Jet Injectors and Hepatitis C Infection as it Relates to Service Connection, Veterans Benefit Admin. (VBA) Fast Letter No. 04-13, 211 (April 29, 2004).
  • (Weniger, 2003) Weniger BG. Jet Injection of Vaccines: Overview and challenges for mass vaccination with jet injectors. Innovative Administration Systems for Vaccines (conference). Rockville, Maryland, USA, 18-19 December 2003.

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December of 1977 Summary

June 13, 2017

The Special Investigations Section summarized it’s findings of the Ped-O-Jet by stating,

Although there is a lack of epidemiologic data implicating jet injector guns in the transmission of viral hepatitis B, we feel that the remote possibility of transmission would be increased by improper use of the gun.  For example, our in vitro studies showed that a massively contaminated nozzle was capable of contaminating the injected fluid for at least two subsequent shots; if the gun was not properly pressed on a patient’s arm during injection and the skin was torn, it is conceivable that such massive contamination may occur in an in-use situation.  We did not demonstrate such carry-over of HBsAg in our in vivo studies, but these experiments were not designed to simulate a worst-case condition as described.  A more definitive statement regarding the safety of jet injector guns with regard to hepatitis B transmission is dependent upon specifically designed prospective seroepidemiologic studies.

The irony of the situation is befitting—the location where the CDC secretly requested epidemiological evidence to further assess the risk of jet injectors was thirty-years later turned over to a government agency that serves precisely the population who was most impacted by jet injectors—military veterans.

Veterans have long blamed jet injectors as one of the sources for the high prevalence of Hepatitis C amongst the now older veteran population.  Jet guns were widely used within the military to deliver numerous immunizations until being banned in 1997.  The VA acknowledges the nexus as “biologically plausible” but to date refuses to recognize jet guns as an official risk factor.

In light of this report, the true historical account of jet injectors demonstrates the Ped-O-Jet came under investigation by the CDC in 1977 from the presence of blood during mass vaccination campaigns.  The full details of the report by the Hepatitis Laboratories Division demonstrated the possibility of transmission of blood and viral hepatitis.  The report signified concern, not relief, over the device.

The researchers did note the lack of epidemiological data implicating the devices.  That is to say there was a lack of any known outbreaks due to jet injectors.  However, this was an illogical point even for that time period.  Knowledge of the asymptomatic progression of serum hepatitis and the recognition of a new hepatitis virus, called non-A, non-B Hepatitis were known throughout the mid- to late-70s and should have brought heightened awareness and the exercising of precautionary measures.

Development of more precise Hepatitis B assays have made detection of low levels of Hepatitis B surface antigen possible.  DNA hybridization, for instance, can detect Hepatitis B surface antigen in solutions 1,000 times smaller than within the method used by the Special Investigations Section.  Therefore, based upon the methods used by the Special Investigations Section, it is highly possible that transmission could have occurred and gone undetected within their experiments.

The final conclusion by the Hepatitis Laboratories Division suggested further studies be implemented.

More Questions Than Answers
After reading this report more questions than answers arose.  For instance, what did Deputy Director of the Hepatitis Laboratories Division, Martin Favero, do upon receiving the report in December of 1977?  Did he pass the report along to CDC Headquarters in Atlanta?  Did he wish to implement another study?  Was he going to inform the manufacturer of the Ped-O-Jet of the test results?  Or did he assume the responsibility now befell upon others to create seroeopidemiological studies?

Attempts to reach out to Mr. Favero were made.  Although, he had asked Norman Petersen, the lead investigator of this study, to speak on his behalf.

Former Chief Norman Petersen explained in a recent communication,

The report you cite was a routine quarterly report that was submitted by the Special Investigations Section to Dr. Favero as a means of documenting the work done in the past quarter.  These reports were widely distributed to an established list of interested readers as well as to the CDC chain of command in Atlanta.

Petersen added, “While it has been 40 years since the writing of the report, I do not recall that the findings resulted in further investigations by our group.  At the time we, and CDC in general, were more interested in whether jet injectors were found to be a significant risk factor in the transmission of hepatitis B in seroepidemiologic studies involving real-life activities.”

The question arises, how does a lab inquire about the possibility of Hepatitis B transmission via jet injectors, discovers transmission is possible and then does nothing afterwards?  Secondly wouldn’t the possibility of transmission demonstrated within the in vitro experiments prompt the lab to inquire about the degree of transmission under worst case scenarios?

The CDC unequivocally acknowledged the jet gun risk in 1977 but viewed the benefits of these devices as a tool for mass immunizations outweighed the risk of transmission.

Mr. Petersen said so himself.  “Although the observed risk of contamination of jet injectors is recognized, the risk-benefit ratio of their use in mass immunization programs is an equally important public health factor.”

CDC’s decision in 1977 to disregard transmission via jet injectors is shocking and disheartening.  Although this report was disseminated within CDC and to a limited number of researchers, it was never made known to the general public.  Thus the public was never given informed consent on the risks of receiving immunizations with such devices or the option of whether or not to partake in this method of vaccination.  An agency solely established to protect the health of its citizenry should not have gambled on whether an outbreak would arise from jet injectors.

In 1985 an outbreak did arise and the CDC was called upon to retest the safety of jet injector devices.   Next Article – Part 2 – CDC Retests the Safety of Jet Injectors in 1986

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Jake The Chimpanzee – In Vivo Experiments

June 9, 2017

Petersen, Bond and Carson then conducted a series of tests to assess if the Ped-O-Jet would become contaminated after injecting an animal already infected with hepatitis B surface antigen (HBsAg).  Two male chimpanzees were used: Jake an adult chimpanzee weighing 145 pounds and a juvenile chimpanzee (name unknown) weighing 44 pounds.  Both chimps were sedated with ketamine for the experiment.

In this in vivo experiment—an experiment taking place in a living organism—a 0.5 ml sterile saline injection was given with a sterile Ped-O-Jet to the HBsAg-positive chimpanzees.  The Ped-O-Jet was firmly held against the skin during the administration of the injection and for three-seconds after the injection.  Following the injection the Ped-O-Jet was fired into a vial and the ejected fluid tested.  If the fluid was HBsAg-positive it would implicate the jet injector as a vehicle in the cross-contamination of viral hepatitis.

Jet Infectors - Phoenix Field Station In Vivo study

Special Investigations Team testing a Ped-O-Jet injector on a chimp in 1977

Detection of blood and HBsAg were obtained using methods viable in 1977 and which are no longer relied upon.  Nonetheless, the results from the in vivo experiments were inconsistent.  For Jake, the adult chimpanzee, one sample from the injection site tested positive for occult blood by Hemastix (urine dipstick) and positive for HBsAg by radioimmunoassay (RIA) using Ausria II, while the remaining four injection site samples were negative.  For the juvenile chimp, 4 out of 5 injection sites were positive for occult blood but all five were negative for HBsAg.  The Ped-O-Jet was swabbed but all samples were negative for HBsAg.  Results of the ejected fluid, the most critical test within the experiment, were also all negative for HBsAg.

The researchers concluded, “from these in vivo experiments that jet injector nozzle surfaces and interior surfaces of the gun are apparently not easily contaminated during actual use.”  The researchers further stated, this experiment only tested conditions under normal use and did not represent a “worse-case condition.”

Although not part of the original report, it is interesting to note that trauma to the injection sites were observed.  Walter Bond recalled the experiment many years later in an email with a colleague-friend.  Bond stated upon visiting Jake in the animal quarters the following day that the injection sites looked “agggh!”

Results No Longer Valid
The Phoenix Labs’ radioimmunoassay method of HBsAg detection, albeit novel for 1977, quickly became outdated.  Advances in science ushered in more precise Hepatitis B assays capable of detecting extremely low levels of HBsAg.  These advances made the results of the Special Investigations Team no longer valid.

Imagine using a magnifying glass.  Several years later, a more powerful lens with a greater magnification emerges allowing things previously unseen to be observed.  Very similarly advances in medicine have allowed for low levels of Hepatitis B surface antigen previously unseen to be observed.

In 1984, Feinman and colleagues found DNA hybridization to be a far more accurate tool than radioimmunoassay in detecting low levels of HBsAg.  Precisely 1,000 times better.  Radioimmunoassay detects HBsAg in dilutions as small as 1/ 100,000 milliliters or rather 10-5 ml.  Whereas DNA hybridization detects as small as 1/ 100,000,000 milliliters or rather 10-8 ml within the same samples (Feinman et al., 1984). This is a huge difference!

“DNA hybridization is the most sensitive method for detecting hepatitis B virus (HBV) infection.  In situations with low virus levels it may be the only indicator of the presence of infectious hepatitis B virus,” wrote Feinman in 1984.

The discovery by Feinman and colleagues made HBsAg detectable in microscopic levels previously unheard of in the medical community.  With this method they found the minimum known volume of blood capable of transmitting Hepatitis B virus was 100 million chimpanzee-infectious doses per milliliter (Feinman et al., 1984).  Former Lead Researcher on Vaccine Technology within the CDC, Dr. Bruce Weniger stated, “This converts to 10 picoliters (10-8 ml) of HBV-infected blood transmitting infection, well below the sensitivity to detect blood by human vision, by common urine dipstick, and by non-PCR HBV assays” (Weniger, Jones & Chen).

Therefore, the radioimmunoassay used by the Phoenix Lab, a non-polymerase chain reaction Hepatitis B virus assay, could not detect positive samples within such low levels.  Neither would the Hemastix urine dipstick be able to detect such low levels.  These tests would give a false-negative, or rather would falsely deem a positive sample to be negative.  Ultimately, low levels of infectious Hepatitis B surface antigen could have been transmitted within this study and could have gone undetected.

For any critics who would argue that such low levels of blood would not be infectious or carryover to the next vaccinee…think again.  As stated within the last article, subsequent research on jet injection has demonstrated cross-contamination of blood (Hoffman et al., 2001; Hoffman et. al., unpublished), infectious material (Brink et al., 1985), and the Hepatitis B virus (Kelly et al., 2008) in such low levels.  In fact, in several samples which demonstrated carryover there was no observable bleeding at the injection site.  This means that microscopic levels of blood and viruses were transmitted via jet injectors despite the absence of any visible bleeding.

From these experiments the team summarized it’s findings.

Next Article – December of 1977 Summary


  • (Brink et al., 1985) Brink PRG, van Loon AM, Trommelen JCM, Gribnau FWJ, Smale-Novakova IRO. Virus transmission by subcutaneous jet injection. J Med Microbiol. December 1985; 20(3): 393-397.
  • (Feinman et al., 1984) Feinman SV, et al. DNA: DNA hybridization method for the diagnosis of hepatitis B infection. J Virol Methods 1984;8(3):199-206
  • (Hoffman et al., 2001) Hoffman PN, Abuknesha RA, Andrews NJ, Samuel D, Lloyd JS. A model to assess the infection potential of jet injectors used in mass immunization. Vaccine 19 (2001): 4020-4027.
  • (Hoffman et al., unpublished) Hoffman PN, Abuknesha RA, Andrews NJ, Brito GS, Carrasco P, Weckx LY, Moia LJMP, Silva AEB, Lloyd J. A field trial of jet injector safety in Brazil. (unpublished).
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