THE DEVIL IS INVISIBLE IN THE COLD CHAIN LINKS OF THE SUPPLY CHAIN OF COVID-19 VACCINES

September 25, 2020

Submitted by Devendra Mishra, Executive Director, BSMA 09252020

Developing an effective vaccine is the first step in the war on the Coronavirus pandemic. Then comes the question of how to deliver hundreds of millions of doses that will be required to be kept at sub-zero temperatures. The single greatest challenge and uncertainty in the planning of the supply chain required for the Coronavirus vaccines is the temperature range at which it has to be handled, stored, distributed and delivered to the patient to be immunized. The devil lurks in the links of the supply chain from the vaccine manufacturer to the infusion into the blood stream of a person.

Considerable knowledge is being acquired during the clinical trials of the vaccine candidates. Of the three vaccines in Phase 3 trials, two — one made by Moderna and the National Institutes of Health, the other by Pfizer and BioNTech — need to be kept in a near constant deep freeze. Pfizer expects its vaccine to be stored in temperatures as low as minus 80 Celsius, while Moderna’s will need to be kept at minus 20 Celsius. Another leading vaccine candidate, being developed by AstraZeneca and Oxford University, must be kept cool but not frozen.

CDC has disclosed that the Moderna vaccine comes as a frozen liquid in a 10-dose vial and contains no preservatives. It can be stored in a freezer or in its shipping container if it is replenished with dry ice. It can be stored for up to two weeks at normal refrigerator temperatures (36 to 46 degrees) according to data provided by the Immunization Action Coalition. Once at room temperature it must be used within six hours. The Moderna vaccine will be most likely be stored either at the manufacturing plant or at a McKesson distribution center. When an order comes in, McKesson will ship it directly to the medical facility that ordered it.

Pfizer has designed a special box for vaccines, roughly the size of a large cooler, which will hold a couple of hundred glass vials, each containing 10 to 20 doses of vaccine. The boxes are equipped with GPS-enabled thermal sensors, allowing Pfizer to know where the boxes are and how cold they are. It is planned that dry ice will be added if it gets too warm.

CDC plans to send orders straight to Pfizer, which will ship to the vaccination sites. The Pfizer vaccine will be shipped in a special transportation container filled with dry ice. The box can be topped off with dry ice every five days to keep it at the appropriate temperature. The vaccine comes in five-dose vials without preservatives. The individual vaccine vials can be refrigerated for up to 48 hours but can be held at each of Pfizer’s specially designed transportation containers, which are about the size of a thick pizza box, contains 195 vials, equal to 975 doses. One container can hold five of those boxes, or as many as 4,875 doses.  Because it’s being shipped only in large volumes, the Pfizer vaccine likely would be distributed at larger medical centers or public health departments that have the capacity to vaccinate large numbers of people and have the proper storage facilities on site. Before use, Pfizer’s vaccine will have to be mixed with a special liquid to dilute it, probably something like sterile water. That liquid would be shipped separately. Once it is mixed it must be used within six hours or discarded, according to the Immunization Action Coalition. It requires two doses given 21 days apart.

McKesson, a major drug distributor, has been selected by the US Government to help distribute the coronavirus vaccines. The major U.S. logistics companies, including UPS and FedEx, are expanding their networks of freezers used to ship perishable food and medical supplies and incorporating more stringent requirements. The companies have experience shipping vaccines for other illnesses, including the seasonal flu, but the Covid-19 vaccination effort dwarfs all previous campaigns.

UPS said it was constructing a so-called freezer farm in Louisville, Ky., the company’s largest hub, where it can store millions of doses at subzero temperatures. Instead of building a complex and costly warehouse with deep freeze capability, UPS is installing rows of upright industrial Stirling Ultracold freezers, each capable of holding 48,000 vials. There are 70 freezers so far, but the warehouse could fit a few hundred. A similar UPS center is in the works in the Netherlands.

FedEx is adding freezers that can maintain temperatures as low as minus 80 Celsius in cities including Memphis, Indianapolis and Paris. It is installing additional refrigerated trailers in Oakland, Calif., Dallas and Los Angeles, which could be used for vaccines that need to be served chilled, not frozen.

Early this year, Corning, a 169-year-old glass maker, alerted the Department of Health and Human Services that there would not be enough cold-resistant glass vials to handle a frozen vaccine. With funding from the Government, Corning plans to start producing hundreds of millions of glass vials next year with a new type of pharmaceutical-grade glass that can withstand the coldest temperatures.

As if the challenge were not sufficiently daunting, the world is facing a looming shortage of dry ice, an unexpected side effect of the pandemic. Dry ice is made from carbon dioxide, which is most commonly produced as a byproduct during the production of ethanol. The reduction in automobile driving because of stay-at-home orders, ethanol production has slumped, and so did the supply of carbon dioxide.

Even if there is enough dry ice and chilled warehouses and sturdy vials, everyday pharmacies are unlikely to be equipped to stockpile large quantities of vaccines that require ultracold storage. Nevertheless, they might be able to keep Pfizer’s cooler-size boxes on hand, and Moderna’s vaccine can be stored at less extreme temperatures in the days before it is administered. It is hoped that States have sub-80 (Celsius) freezers at large hospitals and scientific research facilities to serve as a destination for shipments from McKesson.

There are numerous considerations to Covid-19 vaccines: chilled, frozen or cryogenic. While data is beginning to trickle out on storage and shipping conditions for the new vaccines, there are many questions to resolve for actual commercial distribution in the months ahead. The proverbial Devil has to be analyzed and eliminated at every step of the way.

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