by Olivier Ronveaux, WHO, and Mojtaba Haghgou, Vaccine Management Consultant
Maintaining required temperatures in vaccine refrigerators and freezers is one of the more thankless tasks of a cold chain manager as it requires painstaking manual recording of the temperature of each piece of equipment twice daily. Despite the monotony, temperature monitoring is a crucial task, especially in central stores at the national level where millions of doses of costly vaccines are at stake. A 2004 study
of vaccine freezing in Indonesia, for example, found that freezing temperatures were recorded in 74% of shipments. Without careful temperature monitoring, accidental freezing or overheating of certain vaccines can reduce their potency to levels that render them ineffective against disease.
Several countries, among them Sudan and Iran, have found a way to automate the temperature monitoring system saving both time and money while increasing the accuracy and reliability of the monitoring system. While Sudan is a bit smaller in population than Iran, the two countries have a similarly sized number of surviving infants (1,086,000 in Sudan and 1,300,000 in Iran) and handled an almost identical number of doses of vaccines in 2007/2008 (about 108.8 million doses).
Sudan automated its temperature recording system with financial and technical support from the World Health Organization (WHO) Regional Office for the Eastern Mediterranean (EMRO) in 2007. A United Kingdom-based company was contracted for the design, assembly, and installation of the system which cost about £52,000 at the time.
The system includes a network of gas-type temperature sensors (Figure 1) in each cold and freezer room that measures the internal temperature and transmits it wirelessly via a transmitter installed on the roof of each cold and freezer room to a hub. The hub is connected to a computer for saving data. The store manager can also view the data on a monitor in his office (Figure 2). When temperatures exceed 10[sup]o[/sup]C or fall below 0[sup]o[/sup]C, an alarm system sounds a siren in the store and calls the mobile phones of the store staff and the Expanded Programme on Immunization (EPI) manager. The system also sends a short message service (SMS) text to the mobile phones providing information about the specific cold or freezer room and its internal temperature at the time of breach. The system has functioned continuously since February 2007 without interruption or malfunction. A manual system is maintained for backup purposes and is kept on file.
Iran's system is older (2005) and perhaps more impressive because it was manufactured, designed, assembled, installed, and maintained entirely by local companies. Although the cost of the system is unknown, it is likely to be the less expensive of the two systems since it involved no international travel or foreign labor costs. The system is similar to the Sudanese system with the following differences: local products and labor, the connection between the temperature monitor and the modem is wired (not wireless), the connection between the modem and the computer is wireless, and the temperature sensors are digital, rather than gas type.
EPI staff members from many other countries in the region have already toured Sudan to learn about its system, and there is great interest globally in replicating the concept. Since 2007, WHO has established specifications for performance, quality, and safety (PQS) for temperature monitoring systems and protocols for testing such systems. To support decision-making, Optimize is working to establish minimum criteria under which countries should consider installing automatic temperature recording systems. The type of recommended system will depend on the size of the stores, the number of vaccine doses handled per year, and the importance and location of the store.
Download a copy of a recent Optimize report on temperature monitoring systems
in Sudan and Iran.