© Stitching Pictures
The 'cold chain' is vital to much of MSF's life-saving work. But what is it, and how is it done? Pharmacist Kimberly blogs from Uganda...
I was jolted out of bed by the Medical Team Lead from the Yumbe project calling to ask me to send rabies vaccine via cold chain on the 6am truck, for a member of staff who has been bitten by a rodent. It was one of my first nights on mission, I hadn’t fixed a cold chain in about three years, I was half asleep, and this vaccine was going to embark on a 12 hour journey in a Land Cruiser to Northern Uganda. For some reason I felt an overwhelming sense of pressure with this important assignment (albeit a typical occurrence on an MSF mission).
Before I joined MSF the word “cold chain” had no meaning to me. If pushed for a description of a “cold chain” I would have said something like “the process of keeping your beer cold while tailgating at an Ohio State football game”. In reality, for MSF a “cold chain” is a critical component of many activities.
Kim prepares medications for transport. Photo: MSF.
A cold chain is a system to ensure the quality and safety of drugs throughout the movement from the supplier to the patient. In many MSF projects this movement begins in Bordeaux, France, so the journey is long.
There are two types of cold chain - active (refrigerator, freezer) and passive (cooler boxes, vaccine carriers). Close monitoring of a cold chain is important because some drugs/vaccines are sensitive to heat, and others to freezing. For some vaccines, freezing temperatures will permanently destroy the protein, causing the vaccine to become ineffective and more likely to result in local skin reactions.
There is specific equipment used to monitor the cold chain including an alcohol thermometer, LogTag®, Freeze-Tag® (an irreversible indicator of freezing), and the 3M™ MonitorMark™ (monitoring cumulative heat exposure).
Imagine the impact of losing your vaccine supply for a vaccination campaign designed (and ready) to impact thousands of people
The LogTag® is a great battery-operated device that you program to alarm (audibly and visibly) at a certain temperature after a certain amount of time. It’s the size of a stack of five credit cards and has a reading device the size of ½ an ice cream scoop that plugs into the USB port of your computer. The downloaded data (up to 7770 readings) is a graph of the temperatures, including when and how long they were outside the ideal range. The duration of a temperature excursion is a factor in determining if the medication can be used (perhaps with a new shelf-life) or if it needs to be discarded. This makes LogTag® data a critical component in the decision-making process.
When we know a temperature excursion has occurred, we take a variety of steps to determine if the medications can be used or if they must be destroyed. Imagine the impact of losing your vaccine supply for a vaccination campaign designed (and ready) to impact thousands of people.
When you think about some of the places MSF works, you could be overwhelmed thinking about all the things that could go wrong on the journey our medications make from MSF Logistique in Bordeaux, France to the patient. It might surprise you to hear that 95% of the cold chain breaks are for freezing issues, not due to elevated temperatures. Without the proper training people might not know that ice packs must be prepared or “conditioned” prior to use, which can be done by simply allowing the ice packs to begin the melting process.
The good news is that the cold chain arrived without incident and the staff member had no bad outcomes from the mouse bite (except a little teasing).