African nations have experienced a much lower rate of COVID infections than most of the world. Researchers hoped that analyzing PBMCs (a type of blood cell) stored during an earlier influenza vaccine trial would have helped test a hypothesis that people in these countries had stronger immunity against COVID due to exposure to other coronaviruses. Unfortunately, temperature fluctuations in the storage of the cells had rendered them useless for this research, showing the importance of proper storage of biospecimens to preserve fragile molecules.