Hi John,
Your post was informative regarding the implementation of a passive-cooled cold chain to reach remaining populations underserved by the traditional cold chain. You mentioned that SDD refrigerators have not demonstrated target times between repairs greater then 36 months. What has been the time between repairs for SDD refrigerators?
I was wondering if you have seen our post on MKT thermometers. An MKT thermometer would measure the thermal stress on a vaccine in much the same way that a VVM measures the temperature stress.
http://www.technet-21.org/forum/cold-chain-equipment/8587-vvm-mkt-equivalent-and-complementary-concepts
The MKT thermometer could be reset at the beginning of a trip and the MKT temperature at the arrival point would tell you the percent loss of life due to temperature excursions.
A MKT thermometer would be an asset to the new passive-cooled cold chain or it could be used with conventional ice pack carriers.
Sincerely,
Larry Schlussler, Ph.D.