CDC Secretly Conducted Safety Testing of Jet Injectors in 1977

June 5, 2017

The Special Investigations Section within CDC’s Hepatitis Laboratories Division took a keen interest into jet injectors in the Fall of 1977.  Researchers—Petersen, Bond and Carson—noted widespread use of jet guns in mass immunization campaigns along with reports of bleeding at the injection site.  Although not mentioned within their report, the investigation was in the wake of the Swine Flu vaccination campaign of 1976 in which 75 million Americans were immunized.

The presence of blood during the jet gun vaccinations prompted the lab to inquire about the possible transmission of Hepatitis B virus.  It is important to note that the researchers only mention Hepatitis B because blood-borne pathogens like HIV and Hepatitis C would not be identified until 1983 and 1989, respectively.

“An extensive literature search has produced only three articles dealing with jet injection and its possible association with viral hepatitis B transmission,” wrote the researchers.  Although all three articles were editorials and not peer-reviewed studies.  Since a review of the literature failed to provide an adequate answer, the team conducted it’s own set of experiments upon the most widely known jet injector in the world—the Ped-O-Jet.

“We have conducted a series of in vitro and in vivo experiments in the laboratory to assess the degree of HBsAg [Hepatitis B surface antigen] contamination of jet injector guns during use (detection of HBsAg is presumptive evidence of HBV contamination),” stated the report.

1977 CDC - Unpublished Jet Injector Study
Snapshot of the 1977 Jet Injector Report

Firing Into Vials – In Vitro Experiments
Initial investigations unveiled a shocking phenomenon after firing the Ped-O-Jet.  “It was observed that when the device was held horizontally, a drop of fluid would remain on the injection nozzle port after firing,” stated the report.  When the gun was held vertically “the drop would disappear (back into the injection nozzle head) in 3 to 5 seconds.” It was also noted that if the trigger was cocked while the jet gun was held in a horizontal position the drop of fluid immediately disappeared back into the nozzle head. The researchers concluded, “These manipulations causing disappearance of the fluid drop are common during clinical use of the jet injector.”

The researchers were observing the undesirable phenomenon known as fluid suck-back.  This means if blood were upon the nozzle it would be sucked-back into the orifice of the jet gun contaminating the drug reservoir and the next dosage to be fired.

Inventor of the Ped-O-Jet, Aaron Ismach, stated within his 1959 patent that his invention is “free from danger of 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).  In light of the Phoenix Labs investigation, Ismach’s assertion appears to be no more than a puffing statement to promote the sale of his invention.

Next the lab investigated if the jet gun could cross-contaminate the Hepatitis B surface antigen (HBsAg).  In this in vitro experiment—an experiment conducted outside of a living organism such as in a test tube, vial, or culture dish—the jet gun nozzle was artificially contaminated with HBsAg to see if the antigen would be sucked back into the nozzle head and contaminate the next dosage to be fired.  If the ejected fluid of the next shot contained HBsAg the feasibility of cross-contamination of viral hepatitis by jet injection would be confirmed.

Results found, after the nozzle was contaminated, the ejected fluid of the next shot fired was positive for HBsAg in 4 out of 5 (80%) of the samples.  The second shot fired after the nozzle was contaminated was positive in 3 out of 5 (60%) of the samples.  The third, fourth and fifth shots fired were all negative.  These results indicated that once the Ped-O-Jet became contaminated it remained contaminated for the next two consecutive shots.  Putting this into perspective, for every bleeder in the vaccination line the two subsequent persons were potentially exposed to blood.

The researchers also observed “bleeding from injection sites does sometimes occur but only after the injection nozzle has been removed from the skin surface.”  They, like researchers before them (Elisberg, McCown & Smadel, 1956; Darlow, 1970), incorrectly assumed that since bleeding occurred after the nozzle was removed there was no risk in transferring viral hepatitis.  To alleviate this problem, the researchers recommended, “Proper pressure of the nozzle surface against the skin during and after injection should effectively prevent heavily contaminated nozzle surfaces as simulated in our in vitro experiments.”

Today we know that proper pressure of the nozzle surface against the skin would not eliminate the inherent risks of the jet guns.  Even when the devices worked properly they were inherently dangerous.  Subsequent research on jet injection has also shown the occurrence of pathogen transfer without any visible bleeding at the injection site (Brink et al, 1985; de Souza Brito, 1996; Kelly et al., 2008).  Even when the Ped-O-Jet was used correctly, and incorrectly, in an unpublished Brazilian study, the device transferred enough blood to contain blood-borne pathogens despite delayed bleeding or the absence of visible bleeding at the injection site (Hoffman et al., unpublished).

In 1977, Petersen, Bond and Carson correctly concluded, “a massively contaminated jet injector nozzle could potentially transmit hepatitis B” (emphasis added).

Next the Special Investigations Section assessed if the devices would cause cross-contamination when used upon animals.

Next Article – Jake The Chimpanzee – In Vivo Experiment


  • (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.
  • (Darlow, 1970) Darlow HM. Jet vaccination. British Medical Journal 4(734):554, 1970.
  • (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).
  • (Elisberg, McCown, & Smadel, 1956) Elisberg BL, McCown JM, Smadel JE. Vaccination against smallpox. Jet injection of chorio-allantoic membrane vaccine. J Immunol 1956;77(5):340-351.
  • (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).
  • (Ismach, 1962) Ismach, Aaron. “Multi-dose jet injection device.” United States Patent 3,057,349. 9 October 1962.
  • (Kelly et al., 2008) Kelly K, Loskutov A, Zehrung D, Puaa K, LaBarre P, Muller N, Guiqiang W, Ding H, Hu D, Blackwelder WC. Preventing contamination between injections with multi-use nozzle needle-free injectors: a safety trial. Vaccine (2008) 26, 1344-1352.

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