POST 00485E : CHILLED WATER PACKS STUDY

POST 00485E : CHILLED WATER PACKS STUDY 10 August 2002 _______________________________________________________________ As announced in the previous posting, the preliminary results of studies of chilled water instead of frozen icepacks for vaccine transportation to prevent freezing are presented below by Dr. Ümit Kartoglu (mailto:[log in to unmask]) from WHO. _______________________________________________________________ INTRODUCTION In Post 00400E (20 December 2001), I asked several questions that led WHO to conduct a series of studies both in laboratory-controlled and field conditions using chilled water packs during vaccine transportation. I hoped to have the data in hand a long time ago, but the country studies’ preparation took longer than we expected. Although we are not yet in a position to suggest a policy change in vaccine transportation using chilled water packs, the results are so far positive and suggest that chilled water is a safe alternative to using ice during vaccine transportation to prevent freezing. The plan was to test chilled (2°C to 8°C) water packs performance in vaccine transportation at country level. We have planned 6 country studies looking at ambient and inside-the-cold-box temperatures as well as a controlled laboratory study at 43°C and 32°C for 48 hours. Nepal, Turkey and Zimbabwe studies are completed. The one in Southern Sudan is in progress. We are still looking for one country to conduct the study in EMRO region. Another country will join the group from AFRO western coast. The laboratory study was conducted by CSIR, South Africa, under a WHO contract. The above mentioned studies used RCW2/CF, RCW25/CF and insulated boxes. We also used all 4 types of Vaccine Vial Monitors (VVM2, VVM7, VVM 14 and VVM30) on dummy vaccine vials to determine whether vaccine stability was maintained. A new series of tests will be conducted on Blow Kings insulated vaccine carriers during August. We hope to reach a conclusion on a possible policy change for vaccine transportation once all these tests are completed within several months. Full results will be published in a report and will be available to those who are interested. LABORATORY EVALUATION OF VACCINE CARRIER BOXES USING CHILLED WATER PACKS This laboratory evaluation studied the thermal stability of large and small vaccine cold boxes commonly used for vaccine transport (Electrolux RCW25/CF and RCW2/CF). Evaluation utilized two standard 0.3 liter or twenty-four 0.6 liter icepacks in the small and large vaccine cold boxes, respectively. Instead of being frozen, icepacks were filled with tap water and chilled to either 2°C or 8°C (chilled water packs) and tested with vaccine carriers at ambient temperatures of 43°C and 32°C. One set of tests was done without any chilled water packs at an ambient temperature of 43°C to see the difference brought by water packs (in one of the following postings after the idea of this test was explained, it was said that it would not work because cold water does not have any latent heat as in ice and heats up linearly). A set of four VVMs (VVM2, VVM7, VVM14, VVM30) were attached to the dummy vaccine vials to which a thermocouple was also attached. Temperatures were monitored at 5-minute intervals using a Grant Squirrel data logger with thermocouples recording three distinct temperatures for each large vaccine carrier and two distinct temperatures for each small vaccine carrier. In summary, the five tests performed for large and small vaccine carriers were: 1. Load and water packs at 2°C, ambient temperature 43°C 2. Load and water packs at 8°C, ambient temperature 43°C 3. Load at 2°C, no water packs, ambient temperature 43°C 4. Load and water packs at 2°C, ambient temperature 32°C 5. Load and water packs at 8°C, ambient temperature 32°C As for large vaccine carriers, at ambient temperature of 43°C, it took 49 hours to reach 20°C with 2°C chilled water packs and vaccine load, while this period was 37 hours when 8°C chilled water packs were used. The shortest time (5 hours) was measured with no chilled water packs and 2°C vaccine load test. Similar figures for 32°C ambient temperature were recorded as 60 hours and 50 hours (no test was conducted at 32°C with no water pack). VVM readings were recorded both before and after the test. In all tests except for VVM2 with no water packs at 43°C ambient, all 4 types VVMs were found to be acceptable (use the vaccine) before and after. As for small vaccine carriers, at ambient temperature of 43°C, it took 7.5 hours to reach 20°C with 2° C chilled water packs and vaccine load, while this period was 5 hours when 8°C chilled water packs were used. It took only 1 hour to reach 20°C with no chilled water packs and 2°C vaccine load test. Similar figures for 32°C ambient temperature were recorded as 9 hours and 6 hours (no test was conducted at 32°C with no-cold water pack). VVM readings were recorded both before and after the test. In all tests except for VVM2 with 2°C chilled water packs at 43°C ambient, 8°C chilled water packs at 43°C ambient and no water packs at 43°C ambient, all 4 types VVMs were found to be acceptable indicating that the vaccine can be used safely after the test. FIELD EVALUATION IN NEPAL (RESPONSIBLE PERSON : VENKAT AIYER, WHO) In Nepal, five transportation tests were conducted using large RCW25 vaccine carriers, each with twenty ice packs chilled to between 5°C and 5.9°C. Transportation distances had a range of 221 to 584 kms (6 to 27 hours). In all transportation tests, all four VVMs (VVM2, VVM7, VVM14, VVM30) indicated vaccine potency was not compromised. The ambient temperatures had a range from 10°C to 50°C. Yet the vaccine carrier temperatures remained between 5°C and 13°C. This indicated that the insulation of the RCW 25 vaccine carrier was capable of maintaining safe vaccine temperatures with chilled water packs despite high ambient temperatures. Additional tests will be conducted in Nepal to increase the number of vaccine transportation studies. FIELD EVALUATION IN ZIMBABWE (RESPONSIBLE PERSON : SERGE GANIVET, WHO) In Zimbabwe, 11 transportation tests were conducted using insulated boxes for vaccine transportation. Twelve, 0.4 liter ice packs were chilled to between 4°C to 5°C for each transportation test. Transportation distances had a range of 80 to 583 kms (1 hour to 4 days). In all of the transportation tests, all four sets of VVMs (VVM2, VVM7, VVM14, VVM30) indicated that vaccine potency had not been compromised. FIELD EVALUATION IN TURKEY (RESPONSIBLE PERSON : BIRHAN ALTAY, MOH) In Turkey, 10 transportation tests were conducted using insulated boxes for vaccine transportation. Transportation distances had a range of 10 to141 kms (all in one day). Despite using fewer chilled water packs than standard (at 3°C to 6°C), all four sets of VVMs (VVM2, VVM7, VVM14, VVM30) indicated that vaccine potency had not been compromised. __________________________________________________________________ For those who are interested in the study protocol, please contact Dr. Ümit Kartoglu directly at (mailto:[log in to unmask]) ----------------------------------------------------------------------------- ----------------------------------------------------------------------------- CONTRIBUTIONS: Contributions to: or use your reply button! 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