TechNet-21 - Forum

This forum provides a place for members to ask questions, share experiences, coordinate activities, and discuss recent developments in immunization.
  1. Moderator
  2. Vaccines and delivery technologies
  3. Saturday, 16 February 2002
POST 00426E : Needle-free injector for mass immunization campaigns 16 February 2002 ------------------------------------------------------------------ Follow-up discussion on TechNet21 Postings 00405E, 00408E, 00411E, 00147E and 00420E The recent dialogue on how and where to license a new needle-free injector illustrates a larger generic problem with adoption and approval of new technologies in immunization programs that may be worth highlighting and brainstorming regarding possible solutions. Robert Chen, National Immunization Program, CDC contributes the following to the discussion: "The term "appropriate technology" highlights the importance of the context (cultural, economic, risk-benefit, etc.) that should be taken into account if a specific technology (vaccine or mode of administration) is to be used effectively and efficiently. As the attached diagram (from Lancet 1996;347(9013):1496) shows, immunization programs "evolve" with a dynamic relationship between disease, vaccine coverage, and vaccine adverse events. Thus oral polio vaccine with a risk of vaccine-associated paralytic polio (VAPP) on the order of one case per million doses is acceptable in settings where risk of wild polio is real, but becomes unacceptable in settings where wild polio has been eliminated for decades, hence the switch to inactivated polio vaccine in an increasing number of industrialized countries. Analogously, aseptic meningitis after Urabe mumps vaccine (as part of MMR) on the order of 1 case per 11,000 doses (Lancet 1993;341(8851):979-82) was unacceptable in Canada, UK, and Japan (where a safer Jeryl-Lynn mumps component MMR vaccine was deemed affordable), but acceptable in Brazil (Am J Epidemiol. 2000 Mar 1;151(5):524-30 where a similar risk of 1 case per 14,000 doses was found acceptable (presumably due to factors such as affordability and lack of sequelae). There are times, however, that this realistic weighing of risks and benefits in the proper context appear not to work. For example, the rhesus rotavirus vaccine (RRV) was found to cause intussusceptions in the US on the order of 1 case per 10,000 doses. Given the relative low mortality associated with wild rotavirus infection in the U.S., the US advisory committees withdrew the recommendation for the use of this vaccine. Yet in countries where wild rotavirus remain a major cause of morbidity and mortality, the advisory committees are unable or unwilling to recommend the use of RRV due to the "precedent" set by the U.S. A related conundrum may be occurring with needle-free injectors. In the U.S., reuse of disposable syringes is not a public health issue (but needle-stick injury to health care workers are, ?a new OSHA regs) is. In order for a new needle-free jet injector to be widely accepted in the highly liability-sensitive U.S. milieu, it would likely need to have zero (not just negligible) risk of cross contamination (see previous discussion on how the 501(k) equivalency does not affect this). Yet in many developing countries with substantial burden of unsafe injections and little capability for waste management, a new needle-free jet injector with negligible risk of cross contamination may very well be an excellent (if imperfect) step forward from the horrific status quo. Thus, while a 501(k) "clearance" or a full pre-market "approval" in the U.S. would be "nice" to have, it would not be as useful as a full license, production, and usage in a country where: 1) the risk milieu favors acceptance of such a device, 2) the licensing authorities are competent and therefore whose decision is likely to be recognized and accepted by other countries. Unfortunately, WHO can not serve as the international regulatory body. The question is: which countries might be the best candidates for licensing a good but not perfect jet injector? John Lloyd (PATH) responses Michel's comments (POST 00417E) underlining that nothing is risk free. The purpose of the injector tests should be to show that the risks in use are as low or lower than any alternative injection equipment. John further explains that the Sicim injector shared with other contaminating injectors that there was a continuous, contained fluid column between the site of the injection and the vaccine reservoir permitting backflow when the pressure in the injector tailed away. The new injector has a sharp pressure cut-off and a spacer between the site of the injection and the injector to prevent reflux. The same mechanism of contamination is not possible with the new injector. This remark on the relative speed of syringes and needles and jet injectors came from a visit to Brazilian trials by Peter Evans. The speed of delivery with syringes was achieved by pre-filling multiple syringes in advance of the injection process. This procedure is not acceptable. The speed of reconstitution, filling and delivery by syringe was measured in Egypt to be in the region of 12-15 seconds, during the trial of Verlier AD syringes in the 80s. The speed of delivery of Pedojet injections, as tested in the field in Ghana in the late 70s is 3-5 seconds. We need to do the test again, but don't please abandon the speed criterion. Reduced system cost per injection needs to be evaluated properly. The cost advantage is likely to be impressive. The demonstration of the absence of risk has already been made "on the bench". A repeat of the Brazil trial in human subjects would be definitive and quick to execute. Animal tests are likely to delay the process of development while failing to add value above the results achieved on the bench. Submission to the USFDA for pre-market approval (PMA) when they have already provided a 510K waver is not reasonable and would in any case create such a delay to the development process as to risk losing industry interest altogether. ##text##


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