by Michel Zaffran, WHO; Julie Milstien, consultant; and Modibo Dicko, WHO It has long been known that certain vaccines are stable for long periods of time at temperatures outside the standard cold chain protocol of 2[sup]o[/sup] to 8[sup]o[/sup]C. However, until recently, there have been few reasons to consider changing the relatively simple, blanket policy that all vaccines need to be stored between 2[sup]o[/sup] and 8[sup]o[/sup]C. The only exceptions have been occasional "off-label" use of some vaccines for immunizing hard-to-reach populations, such as "out-of-cold-chain" use of hepatitis B vaccine birth dose; use of tetanus toxoid in pregnancy, just before delivery; and the use of oral polio vaccine with or without cool water packs during campaigns. A change in the vaccine storage temperature policy is not easy. It requires a great deal of evidence gathering, licensing and regulatory changes, and careful consideration of the programmatic impact of the change for countries. Depending on the country, such a change may merit new equipment, training, and monitoring to ensure that the new policy is followed correctly and consistently for all applicable vaccines. However, despite the challenges in doing so, a policy change is becoming increasingly necessary for the following reasons: Temporarily removing vaccines from the traditional cold chain is often the only way to provide on-time immunizations to those who are hardest to reach.A large amount of relatively costly vaccines are currently being exposed to freezing temperatures that can damage them. Newer vaccines are much bulkier and much more costly than traditional Expanded Programme on Immunization vaccines. Under the current policy the only way to accommodate new vaccines is to build new cold rooms, buy bigger coolers, and require health workers to carry heavier cold boxes. Because several vaccines are quite stable at temperatures above 40[sup]o[/sup]C for months at a time, refrigerating these vaccines at all times is unnecessary, potentially harmful (due to accidental freezing), and a waste of precious resources. The World Health Organization (WHO) and PATH, through project Optimize, are collaborating with manufacturers, regulatory bodies, countries, and a programmatic working group to take steps toward new policies that allow for vaccines to be handled in a “controlled temperature chain” where certain heat-stable vaccines can be stored at controlled temperatures that are outside of the traditional 2[sup]o[/sup] to 8[sup]o[/sup]C cold chain. To achieve this change, work is ongoing in three streams: 1. Define the regulatory pathway. The process begins by gathering evidence to understand precisely how higher temperatures may impact vaccine potency and delivery in real-world situations for each heat-stable vaccine. A study of this nature is currently underway with the hepatitis B vaccine. This particular vaccine was chosen for its well-known stability to heat, and for the need to reach infants as soon as possible after birth. Positive results from this study will facilitate relabeling the vaccine for its true heat-stability profile, thus giving countries the option to implement new outreach strategies by using the vaccine within a broader, yet controlled-temperature range. 2. Gather more country-level evidence. Country-level evidence can further confirm vaccine temperature stability in real-world settings, thus contributing to the evidence base upon which regulatory issues are decided. It will also generate critical data that will help inform and develop implementation strategies. 3. Provide programmatic guidance. A programmatic working group has been convened to discuss and develop programmatic guidelines for countries to follow should they consider adopting new temperature policies for specific vaccines. When the licensing, regulatory, and programmatic requirements are met, then WHO will be in a better position to consider changes to the blanket temperature storage policy to accommodate different handling requirements for heat-stable vaccines under controlled temperatures. When is a new policy likely to be developed? The hepatitis B study, which will help define the regulatory pathway for a policy change, is ongoing. Results of the laboratory testing are expected by early 2010. If the results are positive, a change in the regulatory license for relevant hepatitis B vaccines could be proposed to allow storage and transport beyond the traditional 2[sup]o[/sup] to 8[sup]o[/sup]C range. However, this is only a first step. Ideally, all vaccines would be licensed to their true stability. While some vaccines will need to remain in the 2[sup]o[/sup] to 8[sup]o[/sup]C range, others will be able to be handled in a broader controlled temperature range, giving countries increased flexibility to deal with an increasing number of vaccines.
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