Impact of CDC’s 1993-94 Unpublished Study – Part I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within the MMWR General Recommendations on Immunization, dated the 28th of January 1994 preceded Grabowsky filing his unpublished draft with CDC in April of 1994.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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