Within CDC’s 1986 investigation the administration conducted a review of the literature on jet injector safety. A review of the literature is a section within a paper that recognizes previous studies and articles that relate to the topic being investigated. The CDC’s review of the literature within their 1986 CDC report and also within their 1990 study stated the outcomes of jet injector studies. However, both failed to appropriately consider the limitations and differences of these studies. For instance:
- British researcher H.M. Darlow found within his 1970 investigation, there was slight detection of radioactive labeled human serum on the nozzles of Port-O-Jet injectors. Despite the fact that he found contamination, he stated “icteric tragedies have been conspicuous by their absence,” meaning there lacked epidemiological evidence, at the time, to support the existence of a problem with hepatitis. Darlow assumed there was no real risk since recipients of the jet injector were not reporting any adverse health affects (Darlow, 1970). However, Darlow’s view does not account for the asymptomatic progression of serum hepatitis.
- Black and colleagues (1978) found, after replicating Darlow’s experiment, no detection of radioactive human serum on the nozzle of a Med-E-Jet. Within the researchers in vitro investigation they administered injections into tissue infiltrated with radioactive isotope. The researchers concluded, “In the demonstrated absence of contamination with blood or tissue fluid, the risk of spreading hepatitis appears remote” (Black et al., 1978). Yet the 1985 outbreak by a Med-E-Jet injector has proven otherwise.
- Abb, Deinhardt and Eisenberg (1981) found the injection sites and nozzle of a Ped-O- Jet were negative for Hepatitis B associated antigens after administering inoculations to two hepatitis B positive patients. However, Abb and colleagues rendered their opinion on a minuscule sample size. Moreover, the researchers failed to conduct the most critical test in determining cross-contamination by failing to test the ejected fluid for Hepatitis B antigens.
- In 1985, Peter Brink and his colleagues studied the risk of virus transmission via jet injection. These researchers from the Netherlands assessed the degree of contamination after administering jet injections to mice chronically infected with lactic dehydrogenase (LDH) virus, a highly infectious pathogen. Results found 16 out of 49 (33%) mice became infected with the LDH virus after receiving injections from a Med- E-Jet injector. Most shockingly, researchers observed “post-injection bleeding was relatively uncommon,” occurring in only two out of 49 (4%) of the mice. Assuming the two bleeders were amongst the mice who became infected with LDH, indicates at least 14 out of 16 (88%) of the mice became infected despite the lack of visual bleeding. This is worth repeating, even though there was no visible bleeding during or after the jet injection, transmission of a highly infectious pathogen still occurred. This study demonstrates cross-contamination of highly infectious virus within microscopic levels via jet injection.
- Brink and colleagues concluded transmission occurred when excessive tissue pressure after the the delivery/dispersion phase of injection caused retrograde flow of the liquid medicament that had mixed with skin tissues, blood, and the LDH virus. This retrograde flow is thought to be responsible for carrying the virus in the reverse path of the injection, out the injection site and contaminating the nozzle orifice of the jet injector. Brink stated until further investigations into the safety of jet injectors are conducted, “it might be justifiable to screen for HBsAg when a patient belongs to a high risk group, or to abandon the jet and give the treatment with individual syringes and needles” (Brink et al., 1985).
- Brink and colleagues noted how several of the above investigations differentiated. Several studies—such as, Darlow (1970) and Abb and colleagues (1981) only delivered intracutaneous jet injections which were shallow injections and elicited less splash back. These studies used an intradermal nozzle, which acted as a spacer to achieve a shallower vaccination within the layers of tissue just under the skin. Therefore, these studies posed a lesser risk and produced negative to minimal contamination than deeper subcutaneous injections, as in Brink’s study, which required direct contact of the jet injector’s nozzle and the vaccinee’s skin. Brink had written, “the investigations cited above were designed to exclude the risk of transmission of virus infection by intracutaneous jet injections. However, subcutaneous jet injections might have a higher risk of contamination, because of the direct contact between skin and nozzle” (Brink et al., 1985).
Failing to note the above differences led readers to assume that the studies referenced were equivalent comparisons. As we have shown these studies were not comparable as they used an intradermal nozzle and were shallower injections which produced less splash-back.
Moreover, it is interesting to note that CDC’s review failed to mention the administration’s investigation of the Ped-O-Jet in 1977. It can not be said that the CDC didn’t know of its previous safety-testing conducted within the agency since Walter Bond, a CDC microbiologist, served in both investigations.
- (Abb, Deinhardt & Eisenburg, 1981) Abb J, Deinhardt F, Eisenburg J. 1981 The risk of transmission of Hepatitis B virus using jet injection in inoculation. Journal of Infectious Diseases 144: 179.
- (Black et al., 1978) Black J, Nagle CJ, Strachan CHL. Prophylactic low-dose heparin by jet injection.Br Med J 8 July 1978;2(6130):95.
- (Brink et al., 1985) Brink PRG, van Loon AM, Trommelen JCM, Gribnau FWJ, Smale-Novakova IRO. Virus transmission bysubcutaneous jet injection. J Med Microbiol. December 1985; 20(3): 393-397.
- (CDC, 1986) Centers of Disease Control. Epidemiologic Notes and Reports Hepatitis B Associated with Jet Gun Injection — California. MMWR 1986;35(23):373-376
- (Darlow, 1970) Darlow HM. Jet vaccination. British Medical Journal 4(734):554, 1970.