Super-cold refrigeration is a new concept to citizens not involved in molecular biology research. It is a requirement of the Pfizer vaccine that has just provided preliminary indication that it might be 90 percent effective. If further research supports this early data, this vaccine could be approved and begin to become available in the next two months. But this vaccine must be kept at a super low temperature and transported in a “cold chain.” Why?

Chemical reactions generally increase with temperature. Therefore, to slow down spoilage—a chemical reaction—we place food molecules in a refrigerator where they remain cooler and chemical reactions are slower. Milk that would spoil in a day now lasts a week in a refrigerator, but still eventually spoils. Kitchen refrigerators operate at between 35° F and 38° F (1.7° to 3.3°C). Our kitchen freezer temperatures are generally around -1° F (-18° C). But molecular interactions still continue to slowly occur and, in the case of this RNA vaccine, it spoils rapidly at these temperatures.