Graphic-Output Temperature Data Loggers for Monitoring Vaccine Refrigeration: Implications for Pertussis

摘要

We conducted the first US study using graphic-output temperature data loggers in quantifying cold chain failure. Fifty-four vaccine refrigerators of a county outpatient health system were studied. Forty-eight percent maintained temperatures of 2°C to 8°C and 24% had protracted periods of temperatures less than 0°C. The correlation between the percentage of refrigerators with freezing temperatures and the pertussis rate for each health region was r = 0.76. The findings suggest that improper vaccine storage may have contributed to recent increases in pertussis rates. From 2001 to 2005, the incidence of pertussis in Harris County, Texas, increased 196% to a rate of 5.6 cases per 100 000. 1 – 3 This elevated rate paralleled a peak in the overall US incidence. 2 Domestic studies attempted to explain the higher incidence by implicating a fall in immunity among vaccinated adults, unvaccinated children causing disease clusters, and seasonal variation. 1 However, a Canadian outbreak during the 1990s was attributed to excessively cooled pertussis vaccine. 4 Vaccine spoilage as a result of cooling has been studied outside of the United States, 5 – 13 although there have been few domestic studies. 7 The purpose of our study was to evaluate the use of data loggers in quantifying the cold cain failure rate within the Harris County Hospital District community health center network. 14 , 15 The health centers are the primary provider of indigent care services in Harris County; they support approximately 580 000 outpatient visits per year.