Low temperature transport and storage solutions for COVID-19 vaccines
Presentation of two options suitable for mRNA vaccines: one using a traditional refrigerated container adapted to storage at -35°C extending the shelf life of dry ice by 2.5 times, the other based on PCM allowing to maintain -21°C for several hours.
Most COVID-19 vaccines – including messenger RNA (mRNA) vaccines – require compliance with very low temperatures for their transport and storage. The Pfizer vaccine requires temperatures between -80°C and -60°C, while the Moderna vaccine requires −30 °C.
Current transport methods use dry ice to maintain the desired temperatures. However, the final stage of distribution is quite challenging, especially for rural or suburban areas, where pharmacies and hospitals may not have the infrastructure required to store vaccines.
In an article published in the International Journal of Refrigeration (1), Oak Ridge National Laboratory researchers present the results of a study – conducted in collaboration with Carrier – aimed at utilising commercially available products, such as refrigerated containers, and retrofit them to meet the vaccine storage temperature requirement. They created a testbed using a lightweight aluminum container equipped with a refrigeration system and vaccine packages. By optimising the cargo layout and storage rack design, constant and uniform temperatures throughout the container could be achieved.
Computational fluid dynamics have shown that, compared with typical 21.1°C ambient storage, using a −35°C storage temperature extended the dry-ice lifetime by approximately 2.49 times. Other factors influencing dry-ice lifetime include vaccine box design, insulation, leakage rate, and dry-ice fill density.
“We significantly increased the dry ice life, providing reliable temperature control and a safe, secure solution for cooling vaccines for transport and last mile storage,” ORNL’s study main author said. (2)
Another solution for transporting mRNA COVID-19 vaccines, but that does not use dry ice, has recently been developed by Thermal Custom Packaging (TCP), a Florida-based company run by doctors. (3)
TCP claims that its lightweight insulated totes can transport between 350 - 2100 doses of Moderna vaccine while maintaining -21°C temperatures for many hours when using the appropriate PCM. The same transport system, by changing the PCM, can maintain a temperature of 0°C to safely store the Moderna vaccine for 30 days and Pfizer vaccine for 5 days.
For more information on the vaccine cold chain, you can consult the IIR-UN environment program "Cold Chain Technology Brief: Vaccines" available in four languages.
(1) https://iifiir.org/en/fridoc/covid-19-vaccine-distribution-solution-to-the-last-mile-challenge-144557 (free for IIR members)
(3) Yahoo News: With Omicron Variant on the Rise, Thermal Custom Packaging (TCP) is Providing Secure Transportation of COVID Vaccine. Link.