Post00347 FREEZING VACCINES

Post00347 FREEZING VACCINES 07 June 2001 CONTENTS 1. DISCUSSION OF DAMAGE TO VACCINES BY EXPOSURE TO FREEZING TEMPERATURES In post Post00343, Vaccine Freezing: Why Is The Cold Chain Too Cold?, 20 May 2001, Andy Tucker, PATH-CVP, Anthony Battersby, FBA, Hans Everts, WHO/EPI, and Soren Spanner, WHO/SEARO, discuss the field situation and technical developments. Chris Caulfield's , Lifelines, earlier post on VVM availability was also in Post00043. In todays posting Soren Spanner, WHO/SEARO, Anthony Battersby, FBA, and Mogens Munck contribute to the discussion. Opinion, comments and additions please: [log in to unmask] or use your reply button ___________________________________________________________________________ The findings of a multi year-multi site study, including a clear description of the failure modes leading to frequent long duration freezing events in refrigerators used for vaccine storage, were reported in Post00339, 4 May 2001, by Soren Spanner, WHO/SEARO, who kindly posted the file of his recent presentation to the Asia Pacific Regional Working Group. Get the file on the web at: ftp://ftp.acithn.uq.edu.au/Technet/1-ClickHereForTECHNETfiles/VAX-Freeze/ Click on the file: WHY IS THE COLD CHAIN TOO COLD.pdf This file is large at 1.8 Mb. It is too large to make available for email download - as most email systems will bounce the file. If you are unable to download the file on the web but still would like it please let us know - we will see if there is another way to get you the file. ___________________________________________________________________________ Date: Mon, 21 May 2001 From: Anthony Battersby Subject: Post00343 VACCINE FREEZING: WHY IS THE COLD CHAIN TOO COLD? To: Technet Moderator Dear Allan, In response to the posting. Andy Tucker: I recently carried out some research on temperatures inside cold boxes. I found it is impossible to keep the temperature above 0*C and have a reasonable cold life. I also found that the temperature falls to the core temperature of the ice pack which is -0.2*C. I also tried using ice packs filled with eutectic fluid. These prevent the problem of freezing temperatures but drastically reduce cold life and make it almost impossible to keep the temperature below +8*C. The WHO test protocol obtains the results that are quoted in the PIS by adding the ice packs at -20*C and then measuring the cold life once the internal temperature reaches 0*C. As this is not a technique that could be used should the cold box contain vaccine I do not understand why this protocol was adopted. At the Harare TECHNET I asked Olivier Mallet of Lifelines if they could make a freeze sensitive VVM. He told me they were working on it. What is the progress? If there are VVMs attached and all the staff know and trust VVMs then distribution at ambient temperatures is feasible. The proviso being that staff really do understand what the VVM means (remember the South African saga about VVMs only being for long term storage). While I was in PNG recently I found staff had no idea about VVMs even when the TOTs had been carried out to teach staff how to use them. Soren: The workers in the field that I met do not know that the internal thermostat is to make things warmer. As far as they are concerned refrigerators keep things cold, so making the scale work in the same way for each thermostat is clearer. Set the thermostats to a higher number and the refrigerator will get colder, set them to a lower number and it will get warmer. John: How many manufacturers will fill using a uniject presentation? Unless it is universal the problem of vaccine availability will become even more difficult and what happens to a country that has set itself up for uniject and then finds that it cannot obtain vaccine in that presentation? How does it work when some vaccine is in uniject and some in vials? I think we would all like to see vaccines taken out of the cold chain, however we have to cope with a range of vaccines, some such as reconstituted measles and BCG are very heat sensitive and others such as Hib and DPT-Hep B expensive. We also have to cope with systems where daily, thousands of users are subjecting vaccines to less than optimal conditions. Our insurance against less than optimal behaviour by workers is to have substantial redundancy in the cold chain. We need to be very cautious before we accept removing vaccines from the cold chain. There is a world of difference between the conditions found in a field trail (such as Lombok) and the day to day reality of an immunisation service. At district level you are likely to have one chest refrigerator and one freezer so, how does taking one vaccine out of the cold chain save money you still have to store other vaccines and make ice packs. Chris Caulfield: What are the categories A,B,C,D. Anthony --- From: "Spanner, Mr. Soren" To: "'Technet Moderator'" Subject: RE: Post00343 VACCINE FREEZING: WHY IS THE COLD CHAIN TOO COLD? Date: Thu, 24 May 2001 I don't think it will help much to have Hep.B out of the CC from District downwards. The damage can happen during transport, at regional or country level, when Hep.B. is stored in ILRs. For Hep. B. the VVM must have a freeze watch to be useful. best regards soren --- From: Mogens Munck To: Technet Moderator Subject: RE: VACCINE WASTAGE Date: Tue, 5 Jun 2001 Hi Allan, I would like to contribute to this discussion. Please see attachment!! Many regards! Mogens ___________________________________________________________________________ 2nd June 2001 Re.: Discussion of Damage to Vaccines by Exposure to Freezing Temperatures I would like to contribute to this discussion by informing on a follow-up to my paper on Eutectics (Glaubers ' salts) that was presented at the Copenhagen Technet Meeting in 1998. Since then Glaubers' salts have been laboratory tested by CSIR, Johannesburg, a WHO approved laboratory. The results from the CSIR laboratory seem to me to be encouraging! - and to indicate that if ice packs are filled with Glaubers' salts instead of water, freeze damage to vaccines could be avoided. Eutectic salts, as you probably know, will freeze and melt at above zero temperatures, thus allowing freezing in the temperature range prescribed for DPT, Hep. B. Vaccines. The same fridge could store these above zero vaccines and simultaneously freeze eutectic ice packs. No part of the fridge would have to be below zero. Similarly, cold boxes and vaccine carriers could be packed with eutectic ice packs that will not expose the vaccines to freezing temperatures. The CSIR report first describes how to prepare Glaubers' salts by mixing the ingredients, and how to fill the ice packs with eutectics. Next it informs on important features like, how long it takes to "freeze" eutectic ice packs in electric fridges and in paraffin operated absorption fridges respectively, and finally the longevity of the eutectic ice packs, when used in cold boxes and vaccine carriers, as compared with use of water filled ice packs. COLD LIFE TEST [Table reformatted to ASCII text] ___________________________________________________________________________ EUTECTIC ICE PACKS AT 32 DEG.C Large Ice Pack: 60 hours at below 12 deg. C. and at least 220 hours at below 20 deg. Small Ice Pack: At below 15 deg. C for almost 17 hours, and below 20 deg. for nearly 60 hours EUTECTIC ICE PACKS AT 43 DEG. C Large Ice Pack: 40 hours at below 12 deg. And at least 120 hours at below 20 deg. Small Ice Pack: At below 15 deg. C for 15 hours and below 20 deg. C for nearly 23 hours WATER FILLED ICE PACKS AT 32 DEG. C Large Ice Pack: 220 hours at below 10 deg. C Small Ice Pack: Nearly 50 hours below 10 deg. C WATER FILLED ICE PACKS AT 43 DEG. C Large Ice Pack: 160 hours at below 10 deg. C Small Ice Pack: Nearly 34 hours below 10 deg. C ___________________________________________________________________________ Please remember that the components of Glaubers' salts are common, readily available salts, and that no patent right is involved. The cost of components should be a little above 1 US dollar per kilo, i.e. much less than the commercial eutectics that cost anything from 5 US$ and upward. I want to present the CSIR laboratory report at the upcoming Technet Meeting in Delhi, and have a discussion, and hopefully an agreement, on going forward with field-testing. I hope that Umit Kartoglu will put this topic on the agenda of the Delhi Technet Meeting. Best regards! Mogens