Variation in Storage Temperatures for Foot and Mouth Vaccine in Cambodia

Abstract

Vaccine efficacy may be influenced by pre-use storage condition. This study assesses vaccine cold storage management and vaccine handling practices at 30 veterinary drug stores spread across the provinces of Pursat (n=10), Kampong Cham (n=9) and Phnom Penh (n=11) in Cambodia. Electronic data loggers were used to record the temperature in each cold storage facility every thirty minutes for a period of thirty days. The findings indicated that vaccines were exposed to freeze temperature for 24-100 hrs (3%-14%) and more than 100 hrs (15%-87%) of time recordings in 8 and 9 facilities respectively. Vaccines were exposed to heat for 254-327 hrs (35%-45%) of time recordings in 3 facilities and between 468-7200 hrs (65%-100%) in 4 facilities. Most of the refrigerators also contained food and/or drinks, leading to the frequent door opening. Vaccines were often stored in the bottom drawers and door shelves, which were the warmest locations within refrigerators in the study. The vast majority of the study refrigerators (93.3%) were not equipped with a maximum-minimum thermometer. Daily refrigerator temperature recording was not practiced in any of veterinary drugstores. This study also highlighted the considerable temperature fluctuations to which vaccines were exposed to a number of refrigerators. The frequent power failures which occur in Cambodia contribute to these temperature fluctuations. This study consequently also investigated the speed and duration of temperature rise in a cold storage facility during a typical power failure in Phnom Penh. The results suggested that corrective training for vaccine wholesalers/retailers and relevant government staff may be a useful first step in attempting to improve vaccine storage conditions, hence, improved potency. Maintenance of vaccine potency is likely to improve the success of vaccination programs in Cambodia. This critical but neglected issue requires improved practices and ongoing monitoring. The results also highlight the need for improvement and solutions to avoid ongoing future exposure of vaccines to freezing, too cold and too hot temperatures, particularly in hot tropical countries like Cambodia.