POST 00422E: Freeze protection in vaccine refrigerators

POST 00422E : FREEZE PROTECTION IN VACCINE REFRIGERATORS Follow-up to Post 00416E 15 February 2002 ___________________________________________________________ Robert Davis of UNICEF thinks that Carib Nelson raises a very interesting question. "My first take", he says "is that it's a promising idea. We have to consider : 1) will both big and small fridge suppliers be willing to incur the added expense of bringing in such an innovation. 2) where will the temperature be measured? Fridges are not isothermic. Will the sensor be placed in the coldest part of the fridge, in deference to the precautionary principle? This has not been manufacturers' practice in the past,certainly not with top openers. They should review their practice in light of the additional protection against bad OPV now afforded by the VVM. 3) what will be the threshold temperature -- 1 degree or higher? Many if not most governments use the temperature range 2°C to 8°C. The choice of the threshold temperature has to take national standards into account. 4) will the same standard extend to cold rooms as to fridges? If so, what do we do with the hundreds of existing positive temperature cold rooms? 5) would GAVI be willing to fund an innovation designed to protect its multimillion dollar investment in cold sensitive vaccines? Søren Spanner also provides the following comments, in quotes and uppercase. The rest is from Carib's original posting. On the proposal to put heating elements in the refrigerators, "IT IS NOT ONLY WHEN THE AMBIENT TEMP IN HEALTH CENTERS GOES BELOW ZERO, IT IS ALSO WHEN THE TEMPERATURE FOR SOME REASON OR THE OTHER FALLS BELOW ZERO IN THE REFRIGERATORS THEMSELVES. THE HEATING ELEMENT MUST HAVE A FIXED THERMOSTAT SETTING (PREFERABLY NON ADJUSTABLE AND ELECTRONIC)." If this could be combined with better controls where the refrigerator will not cool when its temp is below 1°C--regardless of what the operator sets it at--we might have a freeze-proof refrigerator. Obviously this is not a fix for protecting vaccines from freezing during cold-box-with-ice-pack transport. "THE THERMOSTAT, AS IT IS NOW, SHOULD BE ELIMINATED. WE ONLY NEED A FIXED SETTING(SAY 2 TO 4) (PREFERABLY NON ADJUSTABLE AND ELECTRONIC)." Are freezing temperatures within health centers, or wherever refrigerators may reside, a common occurrence? (or is it improper thermostat adjustment that causes most refrigerator freezing)? "IMPROPER THERMOSTAT ADJUSTMENT, HOWEVER IN FSU, EASTERN EUROPE AND DPRK YOU DO GET "FREEZING CENTRES" Finally Allan Bass shares with us a brief press release from the Associated Press that directly relates to this discussion. "Technology Keeps Vaccines Cool" Associated Press (www.ap.org) (12/23/01); Hannah, James Since the Sept. 11 terrorist attacks on the United States, Energy Storage Technologies Inc. has enjoyed a surge in demand for its refrigeration units--which are ideal for keeping vaccines cool. The Centerville, Ohio-based firm's models, which are tightly insulated and have pumps for controlling temperatures within a few degrees, provide an excellent way to preserve the anthrax vaccine. Using the same wax-based liquid technology used to keep takeout pizza hot, Energy Storage Technologies also manufactures a portable cooler that keeps vaccines cool without freezing them. According to company President Lloyd Huff, underdeveloped countries can use its refrigeration systems to preserve vaccines for smallpox, polio, and other diseases. ----------------------------------------------------------------------------- CONTRIBUTIONS: Contributions to: or use your reply button! 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