POST 00855E : COMBINATION VACCINES, LYOPHILIZED VACCINES, DILUENTS AND VVMS

POST 00855E : COMBINATION VACCINES, LYOPHILIZED VACCINES, DILUENTS AND VVMS Follow-up on Posts 00847E and 00852E 13 November 2005 _____________________________________ This posting contains two contributions. The first is from Oleg Benes (mailto:[email protected]) from Moldova. The other, originally in French, is from Philippe Jaillard (mailto:[email protected]) from Bénin. Both express serious concerns. _____________________________________ Dear Michel, I think the topic you have raised is very important. I understand the economical rationale for applying the MDVP for reconstituted pentavalent vaccine and the opportunity to reduce costs and contribute to the sustainability of country programmes. The same time I am convinced that only simple messages and rules have the chance to be applied in a satisfactory and safe manner in the field. We all know how often people in the field are challenged by getting a large variety of packages, labels and presentations for traditional vaccines (provided by different vaccine manufacturers), language/translation issues (the vaccine insert is part of the package box, while vaccine is often supplied by vials). Implementation of each additional antigen makes this picture more and more complex. Based on my observations the current MDVP knowledge and practice in the field is far from satisfactory, even in countries promoting and using it for many years. One of the simplest ways to promote the message was: you reconstitute vaccine - you use it within 6 hours. If the vaccine comes liquid, ready for use, you may use it for a longer time (one month) subject of a) VVM status, b) expiry date, c) cold chain (when no VVM), d) no risk of contamination. Now, we have to change the mind of all workers in the system, and it may not be an easy task. Teaching that some reconstituted vaccines may be used only for 6 (4) hours while others may be used for a longer time will complicate a lot our message. I consider that risks related to the failure of the policy are very high. Because based on the penta-valent example people may extend this policy to other lyophilized vaccines. And consequences may be so dramatic. So, I would suggest to try to experience and assess in the field potential implications for this policy change on local knowledge and practice. The next point is related to using the VVM as a trigger for deciding whether to use the vaccine only during one session, or for an extended time. I would not agree with that. Because the VVM is a temperature exposure indicator and it has nothing to do with risks of contamination of an opened vial. We should keep ours message simple, another way we may risk to compromise appropriate understanding and use of VVMs. Finally I do not like at all the concept of lyophilized pentavalent, when one vaccine is used as diluent for another one. This, again, breaks the rules that vaccines should never be mixed with one syringe and that lyophilized vaccines should not be reconstituted with liquid vaccines. I wonder whether there are some studies on the impact of the implementation of pentavalent on knowledge and practice of health workers related to vaccine safety issues. With best regards, Oleg Benes, Medical Epidemiologist , National Center of Preventive Medicine Chisinau, Republic of Moldova --------------------------- Hello, Just some comments and reflections on Michel Zaffran’s message. The VVM and the MDVP both contribute to costs reduction, sometimes at the expense of vaccine quality just because these tools are not properly used. As for the tetravalent or pentavalent vaccines with a Hib lyophilised component, the suggestion to have a VVM placed on the vial of Hib looks very attractive. However, since the vaccine is reconstituted with DPT or liquid DPT-HepB, it is necessary to have also a VVM on the vial with liquid vaccine. Otherwise there is a risk of adding a product of uncertain quality (DPT or DPT-HepB with no VVM) to a quality product (Hib with unturned VVM). Is there any plan to affix a VVM on liquid vaccines vials? If this is the case, will the message indicating that both vials should have simultaneously unturned VVMs at the moment of reconstitution, be easily perceived? On the other hand, liquid DPTvaccine is sensitive to freezing and the HepB vaccine is destroyed after a short exposure to negative temperatures. A study done by a trainee from the EPIVAC programme has exposed a lot of inadequacies in HepB vaccine conservation in his district (in 55% of health centres, HepB vaccines had been exposed to temperatures below -5 C for 5 days). This leads to believe that such vaccines have lost their potency. This is not an exceptional case and knowledge of the real quality of freeze-sensitive vaccines before administration, is generally insufficient. In such situations, the presence of VVM on the vial of Hib before reconstitution could lead the health worker to believe, that he is administering a good quality vaccine, regardless of the quality of the liquid product. Before placing VVMs on Hib vials, I think it is necessary to improve the quality of vaccine conservation (equipment, staff competence) first by developing, in countries, the knowledge of this quality of conservation and secondly, to improve the way health workers use wastage reduction tools (mastering of VVMs and MDVP –the same study shows that 57% of health workers do not know MDVP). Regards, Philippe Jaillard, Immunizations Logistics Consultant, AMP ______________________________________________________________________________