On-farm storage of livestock vaccines may be a risk to vaccine efficacy: a study of the performance of on-farm refrigerators to maintain the correct storage temperature.

Abstract

BACKGROUND: Livestock vaccines (LV) are often stored on-farm, in a refrigerator (fridge), prior to use and little is documented about the storage conditions during this period. As the quality of a vaccine can be impaired by storage at an incorrect temperature, the present study aimed to evaluate the on-farm performance of farm fridges to maintain the correct storage temperature. From January to August 2014, temperature data loggers were placed on selected farms fridges used to store LV (n&#x2009;=&#x2009;20) in South-West England. RESULTS: Temperature recording data was available from 17 of the 20 farms. Fifty-nine percent of farm fridges had at least one temperature recording above 8&#xa0;&#xb0;C, 53% had at least one recording below 2&#xa0;&#xb0;C and 41% at or below 0&#xa0;&#xb0;C. Internal fridge temperatures attained 24&#xa0;&#xb0;C and dropped to -&#x2009;12&#xa0;&#xb0;C as an absolute maximum and minimum respectively. Fridges tested spent an average of 16% of the total time recorded above 8&#xa0;&#xb0;C. Time of the year significantly influenced the percentage of time above 8&#xa0;&#xb0;C. External and internal temperatures were found to be positively correlated (p&#x2009;<&#x2009;0.001). Statistical significant differences in internal and external temperatures were found between March and August. CONCLUSIONS: The majority of fridges in this study would have failed to keep any stored LV within the recommended storage temperature range. If LV are going to be stored on-farm prior to use, then urgent improvements in this part of the cold-chain are required in order to insure vaccine efficacy is not compromised.