This is the third posting I have made on in-country transport of vaccine. The first two postings opened issues for discussion on vaccine storage temperatures and on optimizing inter-store transfers. This posting focuses on transport for outreach immunization in the context of a passive-cooled supply chain. I invite you to start a dialogue on all three facets of vaccine transport that we could use to review policy and propose revisions or next steps. Outreach services are mobile, provided at a distance from fixed health facilities by walking, cycling, motor-cycling, driving, boating and even flying to a temporary service delivery posts.
Currently, vaccines are transported in carriers and boxes frozen, or at +2C to +8C depending on the type. Diluents must be cool at the moment of reconstitution and they often enter the cold chain at the health centre because this is typically the last stage where active refrigeration is provided. The dis-advantages of the current system is that refrigerators require maintenance, repairs, energy and require scarce electrical skills to install and maintain. They also have performance limits, usually able to operate up to +43C. These characteristics suit many situations but the more remote rural areas, especially those with extreme temperatures are a major challenge. It is precisely these areas where the population is hard to reach and immunization and other health services have not been provided.
Technology to help extend immunization to these remaining populations is arguably the most challenging target of the next decade. With this in mind, consider a cold-chain based on passive cooling at the level of service delivery, that does not require electrical maintenance, that has no limits to ambient temperature and which is robust enough to resist hard wear for decades. Such a passive system might rely on a ‘hub’, a fixed district facility where cold-packs are ‘charged’ to cool highly insulated containers that are used to store vaccines at the health centre for a month before they need a re-charge. Depending on the situation the containers may be transported to outreach sites by a vehicle, or the vaccine for outreach is transferred to a smaller high performance carrier cooled by designated icepacks drawn from the container. Diluents will be cooled on site at the time of the immunization session by an innovative portable device and the conditions of storage will be remotely monitored.
Note: S.I.A = Special Immunization Activity; ie. Elective campaigns for polio, MNT, measles and outbreak control
The figure illustrates one scenario for outreach to show equipment needs (new equipment starred). Most of the equipment listed is new and either recently available via WHO/PQS or will be available soon. The system is still being field tested and expected to be available at competitive whole-life costs to conventional equipment while being able to operate more reliably in more extreme conditions.
In the spirit of transparency, if you are engaged in this new development please share news of progress with Technet and if you have not already given your views, we would welcome to see them presented here for the discussion.
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