POST 00847E : SEEKING YOUR OPINION

POST 00847E : SEEKING YOUR OPINION 26 October 2005 _____________________________________ Michel Zaffran (mailto:[email protected]) from WHO requests your opinions on the topic below. If you wish your opinion posted, please send a copy to TechNet. _____________________________________ COMBINATION VACCINES, LYOPHILIZED VACCINES, DILUENTS AND VVMS 1. WHO recommendation is that lyophilised vaccines should be discarded 6 hours after reconstitution or at the end of the immunization session for which they have been reconstituted, whichever comes first. Indeed, lyophilized vaccines do not contain preservatives and there is therefore a high risk that they could be contaminated and become a very good medium for bacterial or other pathogens growth, thus a hazard to the vaccine recipient. 2. When VVMs were introduced on lyophilised vaccines (measles, BCG, Yellow Fever), manufacturers were requested to put it on the cap of the vial so that, when the vaccine is reconstituted, the VVM is thrown away. This way the health worker cannot read the VVM and use it as an indication that the vaccine can be kept longer. 3. With the advent of combination vaccines, we are now being faced with situations where some lyophilized vaccine (Hib) can be reconstituted with a liquid vaccine containing a preservative (DTP or DTP-Hep B). The question has come up of whether there would be a simple way to advise health workers that, in some specific case, they can keep the reconstituted vaccine vial, (following the conditions of the Multi-Dose Vial Policy) and not run the risk of confusion created by this situation where :"some lyophilized vaccines can be kept after reconstitution and others cannot" …. Provided laboratory contamination studies confirm that indeed the Multi- Dose Vial Policy applies to these cases, i.e. lyophilized vaccines reconstituted with another vaccine containing preservatives (example of DTP-HepB with lyophilised Hib for instance), the proposal we would like your feedback on is whether this can be done by asking that the VVM be affixed on the label of the lyophilized vaccine. So, for instance, in the case of Hib lyophilized vaccine reconstituted with a DTP-Hep B liquid vaccine, the VVM on the Hib vial would be on the label, it would match the stability of the reconstituted product (DTP-HepB- Hib) and the multi dose vial policy could apply on the fully liquid reconstituted vaccine. The advantage would be that the Multi dose vial Policy could be applied to 10 dose vials of combination vaccines thus making it potentially more economical than singe dose presentations Of course, the change would only apply to those vials of vaccines which are supplied through UN agencies and prequalified for reconstitution with preserved vaccines and would be based on 1) the data on the effectiveness of the preservative in the reconstituted vaccine and 2) the data on the stability of the reconstituted vaccine. Risks that we consider may be possible (may not be exhaustive) * The Hib vial is used with another diluent than the DTP-HepB with thiomersal (the risk is similar as for any lyophilized vaccine of a wrong diluent being used) * The final reconstituted product is put back into the DTP-HepB vial and the wrong VVM is therefore used to monitor heat exposure (unlikely since this would go against usual practice) * Health workers do get confused by the new message and keep other lyophilized vaccines beyond six hours after reconstitution (the risk that this happens may be low but outcome could be very serious if this happens) . * Health workers do not pay attention to VVM or do not know what it is and discard the vial after 6 hours anyway (The risk is of increased wastage) . A question is also raised as to what text will be on the label of the Hib vial - since it will contain initially Hib vaccine, the label will normally say "Hib" but the vial will also eventually contain the reconstituted DTP-HepB-Hib vaccine which can in principle be kept for several days -. We would appreciate your views on the above suggestion, any pro or con of moving in that direction would be appreciated Note that this particular question raises many other questions related to the current situation in the field with lyophilized vaccines where vials of diluents are very seldom available in quantities matching the lyophilized vaccine vials. Since the two vials are not packaged together, the likelihood that they end up together in the health center is small. We have many reports of such mismatch. Could readers of the TechNet Forum also comment on whether they have noticed similar issues with combination vaccines (DTP-HepB + Hib or DTP+ Hib) Michel Zaffran Coordinator, Access to Technologies Immunization, Vaccines and Biologicals WHO Family and Community Health Geneva, Switzerland ______________________________________________________________________________ _________________________________ Visit the TECHNET21 Website at http://www.technet21.org You will find instructions to subscribe, a direct access to archives, links to reference documents and other features. ______________________________________________________________________________ To UNSUBSCRIBE, send a message to : mailto:[email protected] Leave the subject area BLANK In the message body, write unsubscribe TECHNET21E ______________________________________________________________________________ The World Health Organization and UNICEF support TechNet21. The TechNet21 e-Forum is a communication/information tool for generation of ideas on how to improve immunization services. It is moderated by Claude Letarte and is hosted in cooperation with the Centre de coopération internationale en santé et développement, Québec, Canada (http://www.ccisd.org) ______________________________________________________________________________