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  2. Vaccines and delivery technologies
  3. Tuesday, 15 January 2002
POST 00408E Follow up to Post 00405E 15 January 2002 ____________________________________________________________ In Post 00405E, Darin Zehrung < mailto:dzehrun@path.org > had informed us of the development of an improved jet injector for mass immunization within the United States. Michel Zaffran < mailto:zaffranm@who.ch > is concerned about FDA regulations for the approval of such a device. To his knowledge, in the past, the 510 (K) regulation of the FDA did not look at the risk of transmission of bloodborne pathogens. The "PedoJets" and "Immojets" which had a huge potential for cross contamination had all been granted a 510 K approval by FDA. He is asking if the FDA requirements changed? Were these jet injectors actually tested in animals or in humans to verify that there is a zero risk of cross contamination. In some developing countries, given the prevalence of Hep B and HIV, if the jet injector carries even a very small probability of cross contamination, I do not believe that we could ethically recommend its use. There is a huge difference in an unsafe injection being given by a Health worker who reuses of a non sterile syringe (knowing that this is unsafe) with an unsafe injection given with an equipment (Jet injectors) which is believed to be safe but is not. Darin replies that it is true that many earlier devices, such as the Pedojet, were either granted 510(k) market clearance by the FDA or were cleared for use prior to 1976 (pre amendment). In some instances the 510(k) application included in vitro or in vivo contamination test results (such as Medivax). The BI-3M registration in particular included in vitro data utilizing a fluorescein dye contamination procedure developed at PATH, which provided a "worst case scenario" with regard to potential contamination reflux generated during a jet injection. This procedure targets the 10 picoliter transference threshold established in earlier evaluations of contamination safety. One must also take into account the novel design of the BI-3M which includes a disposable (one time use only) protector cap that is designed to "capture" potential contaminates during an injection. In this design the nozzle orifice does not directly contact the skin surface (injection site), but rather the protector cap is the barrier in-between. The protector cap provides a vastly increased level of safety compared with prior multi-dose jet injectors, such as the PedoJet, which had direct nozzle to skin contact. The benefits obtained from the use of a particular technology should be weighed against the possible risks associated with it. This is an exercise that occurs throughout medicine and medical device development. In the case of the BI-3M, or with any multi-dose jet injector providing cross contamination safety, one must weigh the benefits (rapid/increased coverage for mass immunization campaigns, no sharps waste, no possibility for needle stick injury, no possibility for reuse of contaminated needle and syringe, low cost) against the potential risk. It is for this reason we wish to engage the international public health community in this discussion. By no means do we wish to represent the data generated for the 510(k) registration as a definitive response to the issue of cross contamination safety. With your assistance we endeavor to establish a universally accepted assay platform, protocol, and acceptable level of risk for demonstrating contamination safety in humans. Mary Catlin < mailto:mcatlin@email.arizona.edu > from the Young Women's Research Center at the University of Arizona Cancer Center, notes that the number does not show on the FDA website as having been approved yet. Maybe it is too early. She believes that 510 K approval means that because the device was similar to a previously approved device, developers have had to submit less data on its effectiveness and use. So her first recommendation would be to publish ("make available";) the submitted data so that we know what were the assumptions about how it was sterilized and what tests have been conducted. Much of the risk using this device will be related to "human factors"- our failure to follow the stated directions under conditions of actual use. So in the field trials, test should monitor how people try to sterilize the fluid path, how the new cleaning routines, how they are contaminating the vial spike. Some of this should be done prior to using it on people just to make sure a sterile fluid path can be maintained over multi-days and multiple vials. Then on to the issues of using it on moving people (lacerations) etc. the reference "Device Use Safety" incorporating Human Factors in Risk Management is very good. She says she would use a hazards analysis approach to look at all the critical points where things could go wrong rather than more passive observations. This would allow a better definition of the required conditions of use. This device, like syringes, can't be used safely in all sites. Define what is necessary to use it safely. Recommend that it's use be restricted to those sites. Be ready to separate problems with the device, from user and health systems problems. She thinks the object of field trials should be to define device failure problems, but also to define logistic requirements (Can it be carried by bike? do you need water during it's use? what vial sizes? What do you need to sterilize the fluid path?) and observe the impact on other clinic activities and patient acceptability. Remember user preference does not necessarily indicate safety or effectiveness". ----------------------------------------------------------------------------- All members of the TechNet21 e-Forum are invited to send comments on any posting or to use the forum to raise a new discussion or request technical information in relation to immunization services. Starting in January 2002, TechNet21 e-Forum will have 3 language versions: English, French and Spanish. The comments made in this forum are the sole responsibility of the writers and do not in any way mean that they are endorsed by any of the organizations and agencies to which the authors may belong. ----------------------------------------------------------------------------- CONTRIBUTIONS: Contributions to: or use your reply button! 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