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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