POST 00475E : PROTECTION OF MORE COLD-SENSITIVE VACCINES

POST 00475E : PROTECTION OF MORE COLD-SENSITIVE VACCINES Follow-up on Posts 00391E, 00400E, 00412E, 00419E and 00428E 16 July 2002 ______________________________________________________________ It is a long time that we had a contribution on this topic of protection of cold-sensitive vaccines. Elly Tumwine Rweizire (mailto:[log in to unmask]) country logistician at UNEPI (EPI Uganda) has some comments, operational questions and an interesting suggestion. As his contribution was shared with a few people, we already have a reaction from Robert Davis (mailto:[log in to unmask]) from UNICEF/ESARO and Ümit Kartoglu (mailto:[log in to unmask]) from WHO ______________________________________________________________ We have a problem of fuel and our cold chain is mostly dependant on gas-operated fridges, which have relatively high operational costs. Do we have standard acceptable walkable distance between the service delivery point and the recipients? With sparse population distribution, the problem we have is not the vaccine storage capacity, but icepack freezing to support the outreach programmes. How far can we extent the freezing facilities? Now that the freezing point of DPT-HepB+Hib has pressed a demand to relax the cold chain temperature ranges from 0°C to + 8°C, with a shift to +2°C to +8°C, what do you say about increasing the use of fast cold chain? Before we get VVM on all other antigens, how safely can we relax our cold chain system and preach use of chilled water bottles and not frozen icepacks any more? I was wondering whether you have considered construction of storage racks that could be made with fridges to accommodate vaccine vials. These could even be sized for vaccine carriers. They can be stacked in a refrigerator or freezer. (Some thing similar to what laboratories use for keeping their materials - reagents, specimens). If these were made of plastic, they would solve our concern of avoiding direct vial contact with a frozen icepack when used in vaccine carriers. The quantities of vaccine to health unit become small and the packing boxes end in the districts and not beyond. It is becoming difficult to ensure sustainable supply of cardboard or hard papers at unit level to avoid this contact. While one suggests that the icepacks should be left to melt first, there is a lot of relativity in this. What would be the initial icepack temperature? How much time should one allow for this ice pack to melt? If the ambient temperature is harsh, what would be the effect on the other antigens that may remain at the end of the session? What if the health worker has to stay overnight? Elly ______________________________________ EPI would definitely benefit from a low-tech technology to assure noncontact between the more cold sensitive vaccines and the icepacks in the vaccine carriers. I would suggest, however, that his ingenious idea of a kind of plastic framework ("storage racks") to place vaccine vials in the vaccine carrier at point of use be copied to the Far East low tech manufacturers of vaccine carriers, to whom it could be a viable commercial proposition. Could someone with more artistic talent than the present writer make a sketch of the framework so that Technet readers could picture what the device would look like? Bob _____________________________________________________ Regarding melting of icepaks I would like to refer to TechNet postings 00391 and 00400. It is very difficult to give a length of time for conditioning. Everything depends on the icepack temperature, ambient temperature, number of icepacks you are conditioning. Recently visiting a cold store in Tanzania, we took one icepack out of the freezer and placed it on the table to time the process of conditioning. The icepack was at minus 23° C, and the room temperature was 25° C. It took exactly 1 hour to melt it down to zero degree with some liquid water inside and a big core of ice in the middle. The trick is to shake the icepack and hear the ice floating in it. This means the icepack is ready to go into the cold box. Otherwise, temperature is always below zero which increases the risk of freezing if used. I agree, this is time consuming and would take longer time, say if you have to send vaccines by 7 in the morning, when the ambient temperature will most likely be lower than the one at which the test was made in Tanzania. Ümit _______________________________________ CONTRIBUTIONS: Contributions to: or use your reply button! The TechNet21 e-Forum welcomes new subscribers who are involved in immunization services. SUBCRIBE: To subscribe, send an e-mail to: Leave the SUBJECT area BLANK, do not type anything. In the body text, just write: Subscribe TECHNET21E Surname Name Do not use any accents in your name and surname. 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