Hi John – Thank you for your thoughtful post. I’m providing information that I hope the TechNet community finds informative.
Firstly, I am happy to announce that the first freeze-prevention carrier has passed PQS independent lab testing (including the cool down test) and will be published in the coming days. The PQS upper weight limit specification is the same for the non-freeze free and the freeze-free carriers, so no additional weight allowance was provided to freeze-free carriers.
With regard to your comment that the cold chain community is only focused on specific technologies, I want to clarify that PQS is supportive of, and actively seeking innovations that will contribute to solving cold chain challenges in the field that improves the performance, quality, and safety of cold chain technologies. As you know, careful evaluation of performance trade-offs and potential risks is needed when introducing new technology solutions.
For example, engineered phase change materials (PCMs) have been a topic of interest for perceived benefits in reducing the risk of vaccines being exposed to freezing temperatures. The PQS working group has reviewed material compatibility data and consulted UNICEF and EPI teams in order to understand the benefits and risks of allowing PCM into various classes of equipment. After this review PQS has decided to allow PCM in stationary and portable applications where the PCM is not intended to be removed by users. User removable PCM packs are not permitted at this time. The rationale for the restriction on user-removable PCM packs is too lengthy to address here, but some of the key issues are fatty ester PCM incompatibility with high-impact polystyrene (used in vaccine carriers), PCM migration through plastic containers, and that if PCM packs were accidentally placed in a freezer they would still pose a risk of freezing to vaccines. Some of the research PQS used to inform its decision was posted to TechNet and can be found here: Phase-Change Materials for Vaccine Cold Chain Applications.
Finally, PQS has drafted and submitted for industry comment a specification for actively cooled, portable CCE which is where a product such as Indigo would apply. The value proposition for this category of equipment still needs to be informed by field studies of relevant technology and PQS welcomes feedback from all stakeholders (e.g. equipment producers, country health staff) to help inform the final specification.
I hope these points helped clarify the questions raised in your post.