What happens to vaccine contents when vaccines are not properly stored (i.e., not refrigerated?
Excessive heat or cold exposure damages vaccine, resulting in loss of potency. Excessive cold exposure is as bad, if not worse than excessive heat exposure for most vaccines. Once potency is lost, it can never be restored. Furthermore, each time vaccine is exposed to excessive heat or cold, the loss of potency increases and eventually, if the cold chain is not correctly maintained, all potency will be lost, and the vaccine becomes useless. HPV, MMR, MMRV, rotavirus, varicella, and zoster vaccines are sensitive to light, which also causes loss of potency of these particular vaccines. If you have concerns about your vaccine supply, contact the vaccine manufacturer and the state health department immunization program.
