Burnet Institute, 85 Commercial Road, Melbourne, Victoria 3004, Australia.
Immunization, Vaccines and Biologicals Department, World Health Organization, Geneva, Switzerland.
Bull World Health Organ. 2022 Aug 1;100(8):491-502. doi: 10.2471/BLT.21.287696. Epub 2022 Jun 22.
To evaluate the evidence describing how the controlled temperature chain approach for vaccination could lead to improved equitable immunization coverage in low- and middle-income countries.
We created a theory of change construct from the containing four domains: (i) uptake and demand for the approach; (ii) compliance and safe use of the approach; (iii) programmatic efficiency gains from the approach; and (iv) improved equitable immunization coverage. To verify and improve the theory of change, we applied a realist review method to analyse published descriptions of controlled temperature chain or closely related experiences.
We evaluated 34 articles, describing 22 unique controlled temperature chain or closely related experiences across four World Health Organization regions. We identified a strong demand for this approach among service delivery providers; however, generating an equal level of demand among policy-makers requires greater evidence on economic benefits and on vaccination coverage gains, and use case definitions. Consistent evidence supported safety of the approach when integrated into special vaccination programmes. Feasible training and supervision supported providers in complying with protocols. Time-savings were the main evidence for efficiency gains, while cost-saving data were minimal. Improved equitable coverage was reported where vaccine storage beyond the cold chain enabled access to hard-to-reach populations. No evidence indicated an inferior vaccine effectiveness nor increased adverse event rates for vaccines delivered under the approach.
Synthesized evidence broadly supported the initial theory of change. Addressing evidence gaps on economic benefits and coverage gains may increase future uptake.
评估描述冷链控制方法如何能够提高中低收入国家公平免疫覆盖的证据。
我们从包含四个领域的理论变化结构中创建了一个理论变化结构：（i）对该方法的接受和需求；（ii）该方法的合规性和安全使用；（iii）该方法带来的计划效率提高；以及（iv）改善公平免疫覆盖。为了验证和改进理论变化，我们应用现实主义审查方法分析了已发表的冷链或密切相关经验的描述。
我们评估了 34 篇文章，描述了四个世界卫生组织区域的 22 个独特的冷链或密切相关的经验。我们发现服务提供者对此方法有强烈的需求；但是，要在决策者中产生同等水平的需求，需要更多关于经济效益和疫苗接种覆盖率收益的证据，以及用例定义。当该方法整合到特殊疫苗接种计划中时，一致的证据支持其安全性。可行的培训和监督支持提供者遵守协议。节省时间是提高效率的主要证据，而节省成本的数据则很少。在疫苗储存超出冷链范围能够接触到难以到达的人群的情况下，报告了改善公平覆盖的情况。没有证据表明该方法下交付的疫苗效果较差或不良事件发生率增加。
综合证据广泛支持最初的理论变化。解决经济效益和覆盖率收益方面的证据差距可能会增加未来的采用。
